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1

Exciting Students About Science & Engineering ...  

E-print Network

applications include nanomachines, bioimplants, smart materials, fuel cells, genetic engineering and spaceExciting Students About Science & Engineering ... ASM MATERIALS CAMP® 2013 MATERIALS IN TODAY'S WORLD Materials science and engineering is a study of the relationship between the structure

Evans, Paul G.

2

Communicating the Excitement of Science  

ScienceCinema

In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

Michael Turner

2010-01-08

3

RXTE Observations of Cas A  

NASA Technical Reports Server (NTRS)

The exciting detection by the COMPTEL instrument of the 1157 keV Ti-44 line from the supernova remnant Cas A sets important new constraints on supernova dynamics and nucleosynthesis. The Ti-44 decay also produces x-ray lines at 68 and 78 keV, whose flux should be essentially the same as that of the gamma ray line. The revised COMPTEL flux of 4 x l0(exp -5) cm(exp -2)s(exp -1) is very near the sensitivity limit for line detection by the HEXTE instrument on RXTE. We report on the results from two RXTE observations - 20 ks during In Orbit Checkout in January 1996 and 200 ks in April 1996. We also find a strong continuum emission suggesting cosmic ray electron acceleration in the remnant.

Rothschild, R. E.; Lingenfelter, R. E.; Heindl, W. A.; Blanco, P. R.; Pelling, M. R.; Gruber, D. E.; Allen, G. E.; Jahoda, K.; Swank, J. H.; Woosley, S. E.; Nomoto, K.; Higdon, J. C.; Dermer, Charles D. (Editor); Strickman, Mark S. (Editor); Kurfess, James D. (Editor)

1997-01-01

4

How to Generate Student Excitement in Science  

ERIC Educational Resources Information Center

To successfully generate student excitement in science, teachers need to be flexible regarding their curriculums. Students also need to be open to novel, hands-on experiences. This article describes a student teacher (ST) who taught a science unit on "Our Environment." She had already prepared her lesson and unit thoroughly but she changed the…

Ediger, Marlow

2005-01-01

5

Exciting careers blending engineering, science, and ecology  

E-print Network

Exciting careers blending engineering, science, and ecology New Opportunities Making the world://bee.oregonstate.edu/ecoe Ecological Engineering is: · Ecosystem restoration and habitat design at multiple scales · Watershed · Phytoremediation and bioremediation · Industrial ecology · Constructed wetlands and tidal marshlands · Mitigation

Tullos, Desiree

6

RXTE observations of AGN  

NASA Technical Reports Server (NTRS)

The Rossi X-ray Timing Explorer (RXTE) observed three active galaxies during its in-orbit verification phase: NGC 4151; NGC 4945, and MCG 8-11-11. All three were detected from 2 keV to more than 100 keV by a combination of the proportional counter array (PCA) and the high energy X-ray timing experiment (HEXTE). The PCA contains five, xenon/methane, multilayer, multiwire, gas proportional counters covering the 2 to 60 keV range, while HEXTE is an array of eight NaI/CsI phoswich scintillation counters covering the 15 to 250 keV range. The three active galaxies represent the classes of Seyfert 1, Seyfert 2 and intermediate Seyfert galaxies. The results of the fitting of various models containing partial covering fractions, Compton reflection components and high energy spectral breaks are discussed.

Rothschild, R. E.; Heindl, W. A.; Blanco, P. R.; Gruber, D. E.; Marsden, D. C.; Pelling, M. R.; Jahoda, K.; Madejski, G.; Swank, J. H.; Zdziarski, A. A.; Gierlinski, M.; Hink, P. L.

1997-01-01

7

Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting  

E-print Network

Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting degree programs in computer science.I.E.T.) and bachelor in computer science. The innovative B.I.E.T. degree program provides more hands-on, practical

Fernandez, Eduardo

8

RXTE Observations of Cygnus X-3  

NASA Technical Reports Server (NTRS)

In the period between May 1997 and August 1997 a series of pointed RXTE observations were made of Cyg X-3. During this period Cyg X-3 made a transition from a quiescent radio state to a flare state (including a major flare) and then returned to a quiescent radio state. Analyses of the observations are made in the context of concurrent observations in the hard X-ray (CGRO/BATSE), soft X-ray (RXTE/ASM) and the radio (Green Bank Interferometer, Ryle Telescope, and RATAN-600). Preliminary analyses of the observations are presented.

McCollough, M. L.; Robinson, C. R.; Zhang, S. N.; Harmon, B. A.; Paciesas, W. S.; Dieters, S. W.; Hjellming, R. M.; Rupen, M.; Mioduszewski, A. J.; Waltman, E. B.

1997-01-01

9

INTEGRAL and RXTE Observations of Centaurus A  

SciTech Connect

INTEGRAL and RXTE performed three simultaneous observations of the nearby radio galaxy Centaurus A in 2003 March, 2004 January, and 2004 February with the goals of investigating the geometry and emission processes via the spectral/temporal variability of the X-ray/low energy gamma ray flux, and intercalibration of the INTEGRAL instruments with respect to those on RXTE. Cen A was detected by both sets of instruments from 3-240 keV. When combined with earlier archival RXTE results, we find the power law continuum flux and the line-of-sight column depth varied independently by 60% between 2000 January and 2003 March. Including the three archival RXTE observations, the iron line flux was essentially unchanging, and from this we conclude that the iron line emitting material is distant from the site of the continuum emission, and that the origin of the iron line flux is still an open question. Taking X-ray spectral measurements from satellite missions since 1970 into account, we discover a variability in the column depth between 1.0 x 10{sup 23} cm{sup -2} and 1.5 x 10{sup 23} cm{sup -2} separated by approximately 20 years, and suggest that variations in the edge of a warped accretion disk viewed nearly edge-on might be the cause. The INTEGRAL OSA 4.2 calibration of JEM-X, ISGRI, and SPI yields power law indices consistent with the RXTE PCA and HEXTE values, but the indices derived from ISGRI alone are about 0.2 greater. Significant systematics are the limiting factor for INTEGRAL spectral parameter determination.

Rothschild, Richard E.; /San Diego, CASS; Wilms, Joern; /Warwick U.; Tomsick, John; /San Diego, CASS; Staubert, Ruediger; Benlloch, Sara; /Tubingen U., IAAT; Collmar, Werner /Garching, Max Planck Inst., MPE; Madejski, Grzegorz; /SLAC; Deluit, Sandrine; /Toulouse, CESR; Khandrika, Harish; /La Jolla High School

2006-01-17

10

RXTE observations of MXB 0656-072  

NASA Astrophysics Data System (ADS)

RXTE is currently performing a series of snapshot observations of the recurrent X-ray transient pulsar MXB 0656-072 (= XTE J0658-073), following the report of the detection of a new outburst of this source with INTEGRAL (ATEL #1281). Here we report on the detection of the source in the first two snapshot observations which were performed on 2007 November 14 (starting MJD 54418.233) and 2007 November 15 (starting MJD 54419.488).

Pottschmidt, K.; McBride, V. A.; Suchy, S.; Kreykenbohm, I.; Wilms, J.; Rothschild, R. E.; Kretschmar, P.; Schoenherr, G.; Caballero, I.; Kendziorra, E.; Staubert, R.; Swank, J. H.

2007-11-01

11

Continued RXTE Observations of Three Blazars  

Microsoft Academic Search

This project continued (during Cycle 3 of the RXTE mission) weekly observations of the quasars PKS 1510-089 and 3C 454.3 and the BL Lac object OJ 287. The data were analyzed by the PI and his graduate student. In the middle of Cycle 3, the PI changed the mode of observation of 3C 454.3, based on a report from another

Alan P. Marscher

2000-01-01

12

Continued RXTE Observations of Three Blazars  

NASA Astrophysics Data System (ADS)

This project continued (during Cycle 3 of the RXTE mission) weekly observations of the quasars PKS 1510-089 and 3C 454.3 and the BL Lac object OJ 287. The data were analyzed by the PI and his graduate student. In the middle of Cycle 3, the PI changed the mode of observation of 3C 454.3, based on a report from another astronomer that observations with the Rosat satellite had found a strong confusing X-ray source about 45 arcmin away. The RXTE observations, in which the flux was measured while pointing directly at 3C 454.3 and then 15' from 3C 454.3, in the direction away from the confusing source. The flux decreased considerably, and so it appears that nearly all the X-ray flux measured by RXTE comes from the confusing source rather than the quasar. OJ 287 was detected only at one epoch of the Cycle 3 observations. This corresponded to a particularly quiet period for this source, when its flux at other wavebands was also low. From the single epoch of detection, no conclusions can be drawn concerning the general nature of the X-ray emission from this object. In contrast to the other two sources, the results of the observations of PKS 1510-089, when combined with data from cycles 3 and 4, are very interesting. The RXTE (2.4-20 keV) abd 14.5 GHz University of Michigan Radio Astronomy Observatory (UMRAO) light curves through the end of RXTE Cycle 4 are shown for PKS 1510-089. Visual inspection reveals an obvious correlation between the X-ray and 14.5 GHz light curves. While this is as expected in the SSC model in a source with simultaneous mm-wave (the photons thought to be scattered to X-ray energies) and cm-wave variations, the X-ray spectrum is flat ("energy" spectral index alpha = 0.2-0.5, where F v proportional to v (sup - alpha)) compared with the mm-wave synchrotron spectrum (alpha approximately equal to 0.8). The PI is currently engaged in theoretical work to determine whether this is possible for an SSC model.

Marscher, Alan P.

2000-01-01

13

RXTE and Chandra Study of SS433/W50  

NASA Astrophysics Data System (ADS)

The X-ray binary system SS433/W50 has baffled astrophysicists since its discovery in 1979. W50 has been classified as a Galactic supernova remnant that harbors SS433, an X-ray binary consisting of a compact object accreting matter from a companion star at a super-Eddington rate. The nature of the compact object is still under debate, but it is expelling relativistic jets that interact with W50, causing it to elongate along the jets axis and forming two X-ray lobes. We have studied this system in depth using ROSAT and ASCA (Safi-Harb & Ögelman 1997), RXTE (Safi-Harb & Petre 1999, Safi-Harb & Kotani 2002, 2003), and at millimeter wavelengths (Durouchoux et al. 2000). Data will be presented from both the PCA and HEXTE instruments on board RXTE and will be used to complete the spectral and timing analysis of SS433 at high energies. This analysis is targeted to 1) studying the variations of the spectral parameters as a function of the orbital and precession phases of the binary system, 2) correlating its hard X-ray flux with the radio activity, and 3) probing the emission regions from within the binary system. In addition a 75 ksec Chandra observation of the western lobe of W50 will be presented. This region is of particular interest because it is rich with knots resulting from the interaction of a relativistic jet with a dense medium. The Chandra data provide the highest resolution X-ray image obtained to date. This will be correlated with the high-resolution radio and infrared images. A spatially resolved spectroscopic study, targeted to probe the thermal and non-thermal emission associated with the shock-excited regions, will be presented. This study will be then compared to the previous ROSAT and ASCA analysis, and discussed in the light of a jet/cloud interaction.

Moldowan, A.; Safi-Harb, S.

2004-08-01

14

More Science Activities. 20 Exciting Experiments To Do!  

ERIC Educational Resources Information Center

Science and technology affect every facet of human life. By the 21st century, society will demand that all of its citizens possess basic competencies in the fundamentals of science and the use of technology. As science increasingly becomes the dominant subject of the work place, it is important to begin developing within children an understanding…

Smithsonian Institution, Washington, DC.

15

RXTE Observation of the Tycho Supernova Remnant  

NASA Technical Reports Server (NTRS)

SN1006 [4] and Cas A [1, 9] supernova remnants have been shown convincingly to have a hard X-ray power-law continuum. This continuum is thought to be the synchrotron radiation from accelerated electrons of approx. 100 TeV at the shock fronts. Our goal of AO2 RXTE observation is to detect the hard X-ray continuum and to determine the nature of the continuum from Tycho SNR. A detection of a power-law continuum from Tycho SNR can strongly argue for SNRs are the source of cosmic rays with the first order Fermi acceleration as the energizing process. We report the results of our AO2 RXTE 1 x 10(exp 5) sec observation of Tycho SNR. We detect two components of the X-ray spectrum from Tycho SNR both at better than 3 omega confidence. The best two component models are: bremsstrahlung (kT=2.67 +/- 0.13 keV) + bremsstrahlung (kT=7.07 +/- 2.21/1.72 keV) or bremsstrahlung (kT=2.36 +/- 0.21/0.57 keV) + power-law (gamma=2.58 +/- 0.12/0.09 ). This result is an improvement compaxed with the previous most sensitive X-ray measurements by Ginga which shows Tycho's observed X-ray continuum requires a two-component model to yield acceptable fits with the hard component parameters being highly uncertain. Our RXTE measurements constrain all parameter within 3o, ranges. However, we cannot yet distinguish between thermal and nonthermal models for the hard component. In the followings, we describe what we accomplished in the period covered by the grant proposal.

The, Lih-Sin

1998-01-01

16

Exciting youth about science and engineering : the Stirling Engine class  

E-print Network

The problem of a lack of science and engineering opportunities for youth has been identified. While other programs and attempted solutions exist, a novel approach involving creating self-contained project classes, called ...

Barragán, Patrick R

2008-01-01

17

X-Ray Pulsar Studies With RXTE  

NASA Technical Reports Server (NTRS)

Our activities here at MIT have largely concentrated on four different binary X-ray pulsars: LMC X-4; 4UO352+3O/XPer; 4U0115+63; and X1908+075. We have also recently initiated a search for millisecond X-ray pulsations in RXTE archival data for several bright LMXBs using a new technique. Since this study is just getting under way, we will not report any results here. Using RXTE timing observations of LMC X-4 we have definitively measured, for the first time, the orbital decay of this high-mass X-ray binary. The e-folding decay time scale is very close to lo6 years, comparable to, but somewhat longer than, the corresponding orbital decay times for SMC X-1 and Cen X-3. We find that the orbital decay in LMC X-4 is likely driven by tidal interactions, where the asynchronism between the orbital motion and the rotation of the companion star is maintained by the evolutionary expansion of the companion. Under NASA grant NAGS7479 we carried out RXTE observations of X Per/4U0352+30 in order to track the pulse phase over a one year interval. This effort was successful in tentatively identifying a N 250-day orbital period. However, due to the fact that the observing interval was only somewhat longer than the orbital period, we asked for the observations of X Per to continue as public, or non-proprietary observations. Dr. Jean Swank kindly agreed to the continuation of the observations and they were carried out on a less frequent basis over the next year and a half. After 72 separate observations of X Per, we have the orbital period and semimajor axis firmly determined. In addition, we were able to measure the orbital eccentricity-which turns out to be remarkably small (e = 0.10) for such a wide binary orbit. This has led us establish the birth of a neutron star with a very small (or zero) natal kick.

Rappaport, Saul

2004-01-01

18

RXTE Observations of Several Strong Flares from the TeV Blazar 1ES 1959+650  

NASA Technical Reports Server (NTRS)

Responding to the RXTE Cycle 7 NASA Research Announcement, we proposed to use the RXTE X-ray telescopes to intensively observe the TeV Gamma-ray Blazars Markarian 421, Markarian 501, 1ES 1959+650 and 1ES 1426+428, when their X-ray or TeV Gamma-ray fluxes would surpass preset trigger thresholds. In May and June, 2002, the Blazar 1ES 1959+650 (z=0.048) showed a series of spectacular X-ray and gamma-ray flares. Following the detection of a strong Gamma-ray flare on May 16 and 17 with the VERITAS 10 m Cherenkov Telescope, we invoked intensive RXTE observations, as well as complementary radio, optical and GeV/TeV Gamma-ray observations. From May 18 to August 14, more than 150 ksec RXTE observations were taken, yielding a unique data set with simultaneous RXTE and GeV/TeV Gamma-ray coverage.We used the financial support from the ADP program of NASA s Office for Space Science to perform a comprehensive analysis of the RXTE data. We studied in detail the temporal and spectral characteristics of the source. We collected multiwavelength data from a large number of collaborators, and performed a detailed cross-correlation analysis. Eventually, we interpreted the results in the framework of a Synchrotron-Self Compton model. The most important discovery of our research has been the detection of an orphan gamma-ray flare , not associated with an X-ray flare. The discovery showed conclusively that most models invoked to describe the non-thermal emission from blazars are overly simplistic.

Krawczynski, Henric

2004-01-01

19

The College of Physical and Math-ematical Sciences (CPMS) is excited to  

E-print Network

The College of Physical and Math- ematical Sciences (CPMS) is excited to welcome William "Bill and a variety of inter- active techniques, including the creation of Intelligent Scissors, now featured as Adobe, including the iPhone's GPS and picture capabilities, to extract ge- nealogical information from documents

Seamons, Kent E.

20

Diagnostics of SS433 with the RXTE  

E-print Network

We present analysis of extensive monitoring of SS433 by the RXTE observatory collected over the period 1996-2005. The difference between energy spectra taken at different precessional and orbital phases shows the presence of a strong photoabsorption near the optical star, probably due to its powerful dense wind. Assuming that a precessing accretion disk is thick, we recover the temperature profile in the X-ray emitting jet that best fits the observed precessional variations of the X-ray emission temperature. The hottest visible part of the X-ray jet is located at a distance of $l_0/a\\sim0.06-0.09$, or $\\sim2-3\\times10^{11}$cm from the central compact object and has a temperature of about $T_{\\rm max}\\sim30$ keV. We discovered appreciable orbital X-ray eclipses at the ``crossover'' precessional phases (jets are in the plane of the sky, disk is edge-on) which put a lower limit on the size of the optical component $R/a\\ga0.5$ and an upper limit on a mass ratio of binary companions $q=M_{\\rm x}/M_{\\rm opt}\\la0.3-...

Filippova, E; Fabrika, S; Postnov, K; Seifina, E

2006-01-01

21

Diagnostics of SS433 with the RXTE  

E-print Network

We present analysis of extensive monitoring of SS433 by the RXTE observatory collected over the period 1996-2005. The difference between energy spectra taken at different precessional and orbital phases shows the presence of a strong photoabsorption near the optical star, probably due to its powerful dense wind. Assuming that a precessing accretion disk is thick, we recover the temperature profile in the X-ray emitting jet that best fits the observed precessional variations of the X-ray emission temperature. The hottest visible part of the X-ray jet is located at a distance of $l_0/a\\sim0.06-0.09$, or $\\sim2-3\\times10^{11}$cm from the central compact object and has a temperature of about $T_{\\rm max}\\sim30$ keV. We discovered appreciable orbital X-ray eclipses at the ``crossover'' precessional phases (jets are in the plane of the sky, disk is edge-on) which put a lower limit on the size of the optical component $R/a\\ga0.5$ and an upper limit on a mass ratio of binary companions $q=M_{\\rm x}/M_{\\rm opt}\\la0.3-0.35$. The size of the eclipsing region can be larger than secondary's Roche lobe because of substantial photoabsorption by dense stellar wind. This must be taken into account when evaluating the mass ratio from analysis of X-ray eclipses.

E. Filippova; M. Revnivtsev; S. Fabrika; K. Postnov; E. Seifina

2006-07-10

22

Simultaneous Chandra and RXTE observations of the nearby bright Seyfert 2 galaxy NGC4945  

E-print Network

We analyze recent simultaneous Chandra/RXTE observations of the Seyfert 2 galaxy NGC 4945. The unprecedented spatial resolution of Chandra means we are able to separate the spectra of the nucleus, starburst and superwind regions, while the RXTE data extend the spectrum to higher energies. The extreme absorbing column of $N_H\\sim 4\\times 10^{24}$ cm$^{-2}$ means that the nucleus is only seen directly above 8--10 keV, while the lower energy spectrum from the nuclear region in Chandra is dominated by reflection. By contrast, the superwind is dominated by emission from hot plasma, but the starburst region contains both hot plasma and reflection signatures. To form a reflected spectrum requires that the starburst region contains clumps of cool, optically thick material, perhaps star forming cores, which are irradiated by 7--10 keV photons from the nucleus. Since photons of this energy are obscured along the line sight then this confirms the result of Madejski et al. (2000) that the extreme absorbtion material is disk-like rather than a torus. However, the IR/optical limits on the lack of high excitation emission lines show that by contrast the lower energy photons from the nucleus are obscured in all directions. We discuss the complex absorption structure revealed by these observations, and propose an an overall source geometry in which the nucleus is completely embedded in material with $N_H\\sim 10^{23}$ cm$^{-2}$

Chris Done; Greg M. Madejski; Piotr T. Zycki; Lincoln J. Greenhill

2003-01-20

23

RXTE observations of the Seyfert 2 galaxy NGC4507:  

NASA Astrophysics Data System (ADS)

Preliminary results of the RXTE observation of the Seyfert 2 Galaxy NGC4507 are presented. The observed broadband [4-100 keV] spectrum is intrinsically hard (Gamma = 1.2); an iron line is detected with a relatively high equivalent width (EW = 400 eV). The remaining calibration uncertanties are briefly discussed, as well as the scientific implications of our results.

Guainazzi, M.; Matt, G.; Piro, L.; Robba, N. R.

24

"XMM/RXTE Observations of GX 339-4"  

NASA Technical Reports Server (NTRS)

In March 2003, we performed two simultaneous XMM/RXTE observations of the black hole candidate GX 339-4. Our goal is to compare these data to our prior simultaneous RXTE/ASCA observations (Nowak, Wilms & Dove, 2002). These observations were carried out in timing mode, as opposed to burst mode, and are more complex to analyze than we expected. Specifically, the data suffered from a number of telemetry dropouts (in fact, the standard archive processing failed on these data, and more than a year passed from the time of the observations before the data was delivered to us). Furthermore, the core of the EPIC PSF suffers slightly from pileup and gain shifts. We continue to work on this data, however, and anticipate publishing it within the next academic year. Here we highlight our ongoing work and outline our plans for publication.

Nowak, M. A.; Corbel, S.; Fender, R.; Wilms, J.; Kuster, M.; Bailyn, C.; Coppi, P.

2005-01-01

25

Bat Triggered Target of Opportunity Observations with RXTE  

NASA Astrophysics Data System (ADS)

We propose to trigger RXTE PCA observations of new galactic sources discovered as part of the Hard X-ray Transient Monitor of the Burst Alert Telescope (BAT) on the Swift satellite. BAT can provide an early hard X-ray (15-50 keV) trigger on a moderately bright new source. We need the complementary high sensitivity timing data from RXTE to distinguish between various models for the origin of the new transient. By studying the temporal properties of the source in the early turn-on phase we can distinguish between the early accretion disk flow of a black hole candidate, and the periodic emission from a millisecond pulsar or longer period pulsar. This will allow us to rapidly identify the source class and to publish results from the turn-on phase of newly discovered galactic transients.

Krimm, Hans

26

Long periodicity of Blazar with RXTE ASM, TA and HEGRA  

E-print Network

Long periodicity for Mkn501 during a large flare in 1997 have been reported by TA, HEGRA group. Here, we establish this periodicity with archival data of RXTE All Sky Monitor(ASM), Telescope Array(TA) and HEGRA with a chance probability less than $10^{-5}$. We also find that an origin of 23 day periodicity is related with a change of either a gamma factor of electrons $\\gamma$ or the magnetic field or a beaming factor. And, in order to search for a category which have a long periodicity, we make a periodicity analysis for ten H.B.L. with RXTE ASM. We find a long periodicity for three TeV detected source, Mkn501, Mkn421 and PKS2155-304. There may exist a relation between an origin of a long periodicity and an electron acceleration to a TeV range.

S. Osone; M. Teshima

2002-11-29

27

Search for QPOs in Magnetar Bursts with Swift and RXTE  

NASA Astrophysics Data System (ADS)

We have performed a QPO search in the magnetar bursts observed by Swift and RXTE. We found a low frequency QPO candidate at 45 Hz with 11% amplitude in one burst. We present the results of our search including stringent upper limits and discuss its veracity of the candidate feature in light of aliasing effects that could produce such a feature in bursts whose duration are at a comparable time scale. (*) This contribution presents results from students projects carried out during the 8th COSPAR Capacity Building Workshop on Space Astrophysics with NASA & ESA Missions: Swift, Chandra & XMM Newton (Jan. 20-Feb. 2, 2008; Alexandria, Egypt; http://cais.cu.edu.eg/astro)

Ibrahim, Alaa

28

XTE Observations of Intermediate Polars: RXTE TOO Observations of Supernovae  

NASA Technical Reports Server (NTRS)

Two intermediate polar cataclysmic variables, PQ Gem and AO Psc, were observed jointly with the Rossi X-ray Timing Explorer (RXTE) and ground-based photometry. The analysis of intermediate polars (IPs) is complex because these objects exhibit light curves that behave differently as a function of energy and that behave differently when phased on the orbital or on the spin periods. The presence of two periods in one system is essentially equivalent to analyzing two different X-ray sources. A preliminary analysis of the PQ Gem data was carried out and presented at the Annapolis Workshop on Magnetic Cataclysmic Variables. The final analysis of the data were held up by problems with the background estimation. The RXTE PCA team has released a new version of the background estimator. The PQ Gem must be reanalyzed using the new background. We have also installed a spectral model that calculates the expected emission from an accretion column. That model is undergoing final testing before we apply it to the data.

Schlegel, E.; Swank, Jean (Technical Monitor)

2002-01-01

29

The RXTE All Sky Monitor: First Year of Performance  

E-print Network

The RXTE All Sky Monitor provides a public database that includes more than one year of X-ray monitoring observations (2-12 keV) of X-ray binaries and a few active galactic nuclei. The instrument operates with a 40% duty cycle, and the exposures yield roughly 5 celestial scans per day. There have been 109 source detections, including 16 X-ray transients, the majority of which are recurrent cases. The two sources of relativistic radio jets have exhibited particularly complex light curves and new types of emission states. Progress has been achieved in understanding the outburst mechanism via the reported detection of an optical precursor to the April 1996 X-ray outburst in GRO J1655-40. The ASM has also detected state changes in both Cyg X-1 and Cyg X-3, leading to new constraints on the accretion disk geometry associated with the ``soft/high'' state. X-ray variations are seen in extragalactic nuclei, such as NGC4151 and Mkn501, providing new opportunities for multifrequency timing or spectral studies. The ASM archive empowers observers with the opportunity for state-dependent observing programs with RXTE and other instruments. The ASM also provides a long-term context for source behavior, and this knowledge may be crucial in shaping the interpretation of brief observations with other telescopes.

Ronald A. Remillard; Alan M. Levine

1997-07-30

30

Analysis of RXTE data on Clusters of Galaxies  

NASA Technical Reports Server (NTRS)

This grant provided support for the reduction, analysis and interpretation of of hard X-ray (HXR, for short) observations of the cluster of galaxies RXJO658--5557 scheduled for the week of August 23, 2002 under the RXTE Cycle 7 program (PI Vahe Petrosian, Obs. ID 70165). The goal of the observation was to search for and characterize the shape of the HXR component beyond the well established thermal soft X-ray (SXR) component. Such hard components have been detected in several nearby clusters. distant cluster would provide information on the characteristics of this radiation at a different epoch in the evolution of the imiverse and shed light on its origin. We (Petrosian, 2001) have argued that thermal bremsstrahlung, as proposed earlier, cannot be the mechanism for the production of the HXRs and that the most likely mechanism is Compton upscattering of the cosmic microwave radiation by relativistic electrons which are known to be present in the clusters and be responsible for the observed radio emission. Based on this picture we estimated that this cluster, in spite of its relatively large distance, will have HXR signal comparable to the other nearby ones. The planned observation of a relatively The proposed RXTE observations were carried out and the data have been analyzed. We detect a hard X-ray tail in the spectrum of this cluster with a flux very nearly equal to our predicted value. This has strengthen the case for the Compton scattering model. We intend the data obtained via this observation to be a part of a larger data set. We have identified other clusters of galaxies (in archival RXTE and other instrument data sets) with sufficiently high quality data where we can search for and measure (or at least put meaningful limits) on the strength of the hard component. With these studies we expect to clarify the mechanism for acceleration of particles in the intercluster medium and provide guidance for future observations of this intriguing phenomenon by instrument on GLAST. The details of the nonthermal particle population has important implications for the theories of cluster formation, mergers and evolution. The results of this work were first presented at the High Energy Division meeting of the American astronomical Society at Mt. Tremblene, Canada (Petrosian et al. 2003). and in an invited review talk at the General Assembly of the International Astronomical Union at Sydney, Australia (Petrosian, 2003). A paper describe the observations, the data analysis and its implication is being prepared for publication in the Astrophysical Journal.

Petrosian, Vahe

2004-01-01

31

Absolute Timing of the Crab Pulsar with RXTE  

NASA Technical Reports Server (NTRS)

We have monitored the phase of the main X-ray pulse of the Crab pulsar with the Rossi X-ray Timing Explorer (RXTE) for almost eight years, since the start of the mission in January 1996. The absolute time of RXTE's clock is sufficiently accurate to allow this phase to be compared directly with the radio profile. Our monitoring observations of the pulsar took place bi-weekly (during the periods when it was at least 30 degrees from the Sun) and we correlated the data with radio timing ephemerides derived from observations made at Jodrell Bank. We have determined the phase of the X-ray main pulse for each observation with a typical error in the individual data points of 50 microseconds. The total ensemble is consistent with a phase that is constant over the monitoring period, with the X-ray pulse leading the radio pulse by 0.01025 plus or minus 0.00120 period in phase, or 344 plus or minus 40 microseconds in time. The error estimate is dominated by a systematic error of 40 microseconds, most likely constant, arising from uncertainties in the instrumental calibration of the radio data. The statistical error is 0.00015 period, or 5 microseconds. The separation of the main pulse and interpulse appears to be unchanging at time scales of a year or less, with an average value of 0.4001 plus or minus 0.0002 period. There is no apparent variation in these values with energy over the 2-30 keV range. The lag between the radio and X-ray pulses ma be constant in phase (i.e., rotational in nature) or constant in time (i.e., due to a pathlength difference). We are not (yet) able to distinguish between these two interpretations.

Rots, Arnold H.; Jahoda, Keith; Lyne, Andrew G.

2004-01-01

32

RXTE PCA observations show the Rapid Burster undergoing continuous Type II bursting  

NASA Astrophysics Data System (ADS)

Levine and Remillard (ATel. No. 1939) recently reported that the Rapid Burster (MXB1730-335) has been near 50 mcrab in the RXTE ASM daily average intensities for more than two weeks following the expected time of an outburst. A 1000 s long follow-up observation with the RXTE PCA was performed early on Feb. 24, 2009. The source was found to be in a bursting state like some of those seen from the Rapid Burster previously.

Swank, Jean; Markwardt, Craig; Pereira, Divya; Levine, Alan M.; Remillard, Ronald A.

2009-02-01

33

Exciting Precollege Students and Teachers About Science: Examples from Jefferson Lab  

Microsoft Academic Search

The staff, visiting physicists from 25 countries, state-of-the-art facilities, and the research on the quark structure of matter provide an exciting environment for capturing the interest of and augmenting the experiences of precollege students and teachers. This talk describes the motivational experiences for precollege students and enhancement opportunities for their teachers offered by Jefferson Lab since 1991. For example, the

B. K. Hartline

1997-01-01

34

The RXTE All Sky Monitor First Year of Performance  

E-print Network

The RXTE All Sky Monitor provides a public database that includes more than one year of X-ray monitoring observations (2-12 keV) of X-ray binaries and a few active galactic nuclei. The instrument operates with a 40% duty cycle, and the exposures yield roughly 5 celestial scans per day. There have been 109 source detections, including 16 X-ray transients, the majority of which are recurrent cases. The two sources of relativistic radio jets have exhibited particularly complex light curves and new types of emission states. Progress has been achieved in understanding the outburst mechanism via the reported detection of an optical precursor to the April 1996 X-ray outburst in GRO J1655-40. The ASM has also detected state changes in both Cyg X-1 and Cyg X-3, leading to new constraints on the accretion disk geometry associated with the ``soft/high'' state. X-ray variations are seen in extragalactic nuclei, such as NGC4151 and Mkn501, providing new opportunities for multifrequency timing or spectral studies. The ASM ...

Remillard, R A; Remillard, Ronald A.; Levine, Alan M.

1997-01-01

35

ADVANCES IN THE RXTE PROPORTIONAL COUNTER ARRAY CALIBRATION: NEARING THE STATISTICAL LIMIT  

SciTech Connect

During its 16 years of service, the Rossi X-Ray Timing Explorer (RXTE) mission has provided an extensive archive of data, which will serve as a primary source of high cadence observations of variable X-ray sources for fast timing studies. It is, therefore, very important to have the most reliable calibration of RXTE instruments. The Proportional Counter Array (PCA) is the primary instrument on board RXTE which provides data in 3-50 keV energy range with submillisecond time resolution in up to 256 energy channels. In 2009, the RXTE team revised the response residual minimization method used to derive the parameters of the PCA physical model. The procedure is based on the residual minimization between the model spectrum for Crab Nebula emission and a calibration data set consisting of a number of spectra from the Crab and the on-board Am{sub 241} calibration source, uniformly covering the whole RXTE mission operation period. The new method led to a much more effective model convergence and allowed for better understanding of the PCA energy-to-channel relationship. It greatly improved the response matrix performance. We describe the new version of the RXTE/PCA response generator PCARMF v11.7 (HEASOFT Release 6.7) along with the corresponding energy-to-channel conversion table (version e05v04) and their difference from the previous releases of PCA calibration. The new PCA response adequately represents the spectrum of the calibration sources and successfully predicts the energy of the narrow iron emission line in Cas-A throughout the RXTE mission.

Shaposhnikov, Nikolai [CRESST and Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Jahoda, Keith; Markwardt, Craig; Swank, Jean; Strohmayer, Tod, E-mail: nikolai.v.shaposhnikov@nasa.gov [Astrophysics Science Division, Goddard Space Flight Center, NASA, Greenbelt, MD 20771 (United States)

2012-10-01

36

Life in the Universe: Foundation for exciting multidisciplinary science activities for middle and elementary school classes  

NASA Technical Reports Server (NTRS)

Young students find extra-terrestrial life one of the most intriguing of all topics. A project funded by the National Science Foundation and NASA, and administered by the SETI Institute, is underway to devise science lessons for grades 3-9 that draw upon this fascination. The lessons are designed by teachers and persons with long experience at curriculum design, tested in classrooms, revised and retested. Six guides, each containing some 6-10 science lessons, will be finished by summer, 1994.The theme Life in the Universe lends itself naturally to integrated treatment of facts and concepts from many scientific disciplines. The lessons for two completed guides span the origin of planet systems, evolution of complex life, chemical makeup of life, astronomy, spectroscopy, continental drift, mathematics and SETI (Search for Extra-Terrestrial Intelligence). All lessons are hands-on, interesting, and successful.

Milne, D.; O'Sullivan, K.

1994-01-01

37

RXTE ASM Observations of GRB991216 - A One Hour Old X-ray Afterglow  

NASA Astrophysics Data System (ADS)

The Gamma-ray Burst 991216 (the ``Beethoven" burst) was both very bright itself and also had an unusually bright X-ray afterglow. This afterglow was observed and localized by the RXTE PCA 4 hours after the burst occurred (Takeshima et al. 1999). This position determination then enabled an optical afterglow to be found (Uglesich et al 1999). Serendipitously, the RXTE ASM obtained a sequence of 7 observations covering this source in a period of 11 minutes starting just 1 hour after the burst peak. From these 7 dwells, a flux of 32 +/- 8 mCrabs (1 sigma error) was determined which is consistent with a power-law extrapolation of RXTE PCA flux measurements. While GRB afterglows are generally faint and thus difficult for the RXTE ASM to study, due to its modest collecting area and short observation times, we believe that this unusually bright afterglow has indeed been detected. These results indicate that the RXTE ASM has provided a measurement of an X-ray afterglow light curve at times which have previously not been studied.

Corbet, R.; Smith, D. A.

38

Long-Term Monitoring of PSR B0540-69 with RXTE  

NASA Technical Reports Server (NTRS)

RXTE has monitored PSR B0540-69, the young, Crab-like pulsar in the LMC, since early January 1999 and maintained a phase-connected timing solution. We report on a search for glitches in phase or frequency, changes in the braking index, and a determination of the pulsar position.

Marshall, Francis

2012-01-01

39

A Coordinated RXTE/ASCA Study of Absorption Dips in Circinus X-1 at Phase Zero  

NASA Technical Reports Server (NTRS)

This proposal was for an Rossi X Ray Timing Explorer (RXTE) study of Circinus X-1 with the ASCA satellite for the purpose of studying the iron emission feature during intensity dips. These dips had been discovered previously with ASCA and they appeared to vary in equivalent width and in the energy of the iron K edge. Proper analyses requires good continuum measurements which Rossi X Ray Timing Explorer/Proportional Counter Array (RXTE/PCA) could provide. Also, the PCA data would show any temporal evolution correlated with spectral evolution. RXTE provided 90 ks of data during March 3-5, 1998 which included phase zero which is where the dips usually take place. The ASCA observations were taken by Dr. Neil Brandt of Penn State University. Unfortunately, the source intensity showed far less dipping activity than is typical near phase zero. The light curve exhibited only very narrow sporadic dips rather than some long deep dips necessary for sufficient statistics in the ASCA and RXTE instruments for spectral studies. This prevented us from carrying out the primary goal of the proposal.

Bradt, Hale

2000-01-01

40

RXTE Observations of the Vela Pulsar: The X-ray-Optical Connection  

E-print Network

We report on our analysis of a 300 ks observation of the Vela pulsar with the Rossi X-Ray Timing Explorer (RXTE). The double-peaked, pulsed emission at 2 - 30 keV, which we had previously detected during a 93 ks observation, is confirmed with much improved statistics. There is now clear evidence, both in the spectrum and the light curve, that the emission in the RXTE band is a blend of two separate components. The spectrum of the harder component connects smoothly with the OSSE, COMPTEL and EGRET spectrum and the peaks in the light curve are in phase coincidence with those of the high-energy light curve. The spectrum of the softer component is consistent with an extrapolation to the pulsed optical flux, and the second RXTE pulse is in phase coincidence with the second optical peak. In addition, we see a peak in the 2-8 keV RXTE pulse profile at the radio phase.

Alice K Harding; Mark S. Strickman; Carl Gwinn; P. McCulloch; D. Moffet

1999-11-15

41

Studies of Thermonuclear X-ray bursts using Archival Data from RXTE  

NASA Astrophysics Data System (ADS)

I present results from a project using archival Rossi X-ray Timing Explorer data to study thermonuclear (type-I) X-ray bursts. These bursts occur due to unstable ignition of accumulated H/He fuel on the surface of accreting neutron stars in binary systems. To date we have accumulated 820 bursts from 41 of the more than 80 known burst sources. I will summarise the properties of the sample, and variations in the properties of the bursts as a function of accretion rate, as well as giving details of some of the more exciting results from the study. The data show that photospheric radius-expansion (PRE) bursts, which are thought to reach the Eddington limit, do not all reach the same peak flux for a given source. Instead, the peak fluxes of the PRE bursts vary by (typically) 10-20%, although in 4U 1636-536 the peak fluxes vary by a factor of 4. In 4U 1728-34 we found a correlation between the persistent flux and the peak PRE burst flux, which we attribute to reprocessing of the flux in a warped, precessing accretion disk. However, this mechanism cannot account for variations in the peak fluxes of PRE bursts from all sources. Measurements of the burst energetics and recurrence times are possible using RXTE with much improved precision compared to previous instruments. In the "Clocked Burster", GS 1826-24, hydrogen burns during the bursts via the rapid-proton (rp) process, of particular attention in recent years via theoretical and modelling studies. The burst energies and the variation of alpha (the ratio of persistent to burst fluence) with accretion rate strongly suggests solar atmospheric metallicity, although this appears inconsistent with the corresponding variation of the recurrence time. Possible explanations include extra heating between the burst, or a change in the fraction of the neutron star over which accretion takes place. I will also present more recent results from other sources with which we are gradually probing a wide range of burst regimes. This work was supported in part by the NASA Long Term Space Astrophysics program under grant NAG 5-9184.

Galloway, D. K.; Chakrabarty, D.; Muno, M. P.; Psaltis, D.; Cumming, A.

2003-12-01

42

RXTE, Chandra, and XMM Spectroscopy of the Fe-K Lines and Compton Reflection in Type 1 AGN  

NASA Technical Reports Server (NTRS)

This award pertains to an RXTE observation of the Seyfert 1 galaxy Akn 120. The purpose of the observation was to measure the Fe-K emission line and the Compton reflection continuum with RXTE, simultaneously with Chandra and XMM. Such measurements can severely constrain accretion disk models of the central engine since the Fe-K line emission and Compton reflection are intimately related in terms of the physics of X-ray reprocessing in optically-thick matter. Akn 120 was selected for this study because it is amongst the brightest AGN in its class and has a particularly strong and apparently broad Fe-K emission line. The results could then also be used to lay the ground work for even higher resolution studies with Astro-E2. Unfortunately, the Chandra observation was not performed but a contemporaneous XMM observation was performed by another group of researchers. Those data recently became public and can be compared with the RXTE data. In addition, non-contemporaneous observations with other missions do still provide additional important constraints (for example any non-varying line or continuum emission components can be established and used to reject or preserve various model scenarios). We analyzed the RXTE data and found a strong Fe-K emission line (resolved even with the poor resolution of RXTE), and a strong Compton-reflection continuum (see Fig. l(a)). We found that the results of archival ASCA data on Akn 120 had not been published in the literature so we analyzed the ASCA data too, in order to compare with the new RXTE data. Fig. l(b) shows that the ASCA data also reveal a strong, broad FeK emission line (but the data are not sensitive to the Compton-reflection continuum). We compared our spectral fitting results for the RXTE and ASCA data with the results from XMM and from previous RXTE observations.

Yaqoob, Tahir

2004-01-01

43

Observation of Nonthermal Emission from the Supernova Remnant IC443 with RXTE  

NASA Technical Reports Server (NTRS)

In this paper we present analysis of X-ray spectra from the supernova remnant IC443 obtained using the PCA on RXTE. The spectra in the 3 - 20 keV band are well fit by a two-component model consisting of thermal and nonthermal components. We compare these results with recent results of other X-ray missions and discuss the need for a cut-off in the nonthermal spectrum. Recent Chandra and XMM-Newton observations suggest that much of the nonthermal emission from IC443 can be attributed to a pulsar wind nebula. We present the results of our search for periodic emission in the RXTE PCA data. We then discuss the origin o f the nonthermal component and its possible association with the unidentified EGRET source.

Sturner, S. J.; Keohane, J. W.; Reimer, O.

2002-01-01

44

Swift, INTEGRAL, RXTE, and Spitzer Reveal IGR J16283-4838  

NASA Technical Reports Server (NTRS)

We present the first combined study of the recently discovered source IGR J16283-4838 with Swift, INTEGRAL, and RXTE. The source, discovered by INTEGRAL on April 7, 2005, shows a highly absorbed (variable N(sub H) = 0.4-1.7 x 10(exp 23) /sq cm) and flat (Gamma approx. 1) spectrum in the Swift/XRT and RXTE/PCA data. No optical counterpart is detectable (V > 20 mag), but a possible infrared counterpart within the Swift/XRT error radius is detected in the 2MASS and Spitzer/GLIMPSE survey. The observations suggest that IGR J16283-4838 is a high mass X-ray binary containing a neutron star embedded in Compton thick material. This makes IGR J16283-4838 a member of the class of highly absorbed HMXBs, discovered by INTEGRAL.

Beckmann, V.; Gehrels, N.; Markwardt, C.; Barthelmy S.; Soldi, S.; Paizis, A.; Mowlavi, N.; Kennca, J. A.; Burrows, D. N.; Chester, M.

2005-01-01

45

Joint XMM-Newton, Chandra, and RXTE Observations of Cyg X-1 at Phase Zero  

NASA Technical Reports Server (NTRS)

We present first results of simultaneous observations of the high mass X-ray binary Cyg X-1 for 50 ks with XMM-Newton, Chandra-HETGS and RXTE in 2008 April. The observations are centered on phase 0 of the 5.6 d orbit when pronounced dips in the X-ray emission from the black hole are known to occur. The dips are due to highly variable absorption in the accretion stream from the O-star companion to the black hole. Compared to previous high resolution spectroscopy studies of the dip and non-dip emission with Chandra, the addition of XMM-Newton data allows for a better determination of the continuum, especially through the broad iron line region (with RXTE constraining the greater than 10 keV continuum).

Pottschmidt, Katja

2008-01-01

46

RXTE and Swift Discovery of the Intermittent Source XTE J1704-445  

Microsoft Academic Search

We report the detection of an intermittent source XTE J1704-445 (hereafter J1704). This source was first detected in RXTE PCA scans of the galactic bulge and ridge regions over approximately a month. Because J1704 was near another bright source 4U 1705-440, whose variability can sometimes mask other nearby positions, it took some time to recognize J1704 as \\

C. B. Markwardt; J. H. Swank; M. Klein-Wolt; D. M. Smith

2007-01-01

47

A 0535+26 in the August/September 2005 outburst observed by RXTE and INTEGRAL  

E-print Network

In this Letter we present results from INTEGRAL and RXTE observations of the spectral and timing behavior of the High Mass X-ray Binary A 0535+26 during its August/September 2005 normal (type I) outburst with an average flux F(5-100keV)~400mCrab. The search for cyclotron resonance scattering features (fundamental and harmonic) is one major focus of the paper. Our analysis is based on data from INTEGRAL and RXTE Target of Opportunity Observations performed during the outburst. The pulse period is determined. X-ray pulse profiles in different energy ranges are analyzed. The broad band INTEGRAL and RXTE pulse phase averaged X-ray spectra are studied. The evolution of the fundamental cyclotron line at different luminosities is analyzed. The pulse period P is measured to be 103.39315(5)s at MJD 53614.5137. Two absorption features are detected in the phase averaged spectra at E_1~45keV and E_2~100keV. These can be interpreted as the fundamental cyclotron resonance scattering feature and its first harmonic and therefore the magnetic field can be estimated to be B~4x10^12G.

I. Caballero; P. Kretschmar; A. Santangelo; R. Staubert; D. Klochkov; A. Camero; C. Ferrigno; M. H. Finger; I. Kreykenbohm; V. A. McBride; K. Pottschmidt; R. E. Rothschild; G. Schoenherr; A. Segreto; S. Suchy; J . Wilms; C. A. Wilson

2007-02-20

48

ASCA and Radio/RXTE Observations of GX 339-4  

NASA Technical Reports Server (NTRS)

We have analyzed three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) observations and eight separate Rossi X-ray Timing Explorer (RXTE) observations of the black hole candidate GX 339-4 in its low luminosity, spectrally hard state. Three of the RXTE observations were strictly simultaneous with 843 MHz and 8.3- 9.1 GHz radio observations. All data sets show evidence for an approximately 6.4 keV Fe line with equivalent widths approximately 20-100 eV. 'Reflection models' show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. None of the models fit to the X-ray data, however, simultaneously explain the observed radio properties. We argue that the spatial extent of the observed radio emission is at least 0(10(exp 7 GM/c squared). Timing analysis reveals that all observations save one show evidence of a persistent f(qpo approximately equals 0.3 Hz quasi-periodic oscillations(quasi-periodic oscillations)). The broad band (10-3-102 Hz) power appears to be dominated by two independent processes that can be modeled as very broad Lorentzians with Q approximately less than 1. Similar to Cyg X-1, the hard photon variability is seen to lag the soft photon vaxiability with the lag time increasing with decreasing Fourier frequency. The magnitude of this time lag is seen to be positively correlated with the flux of GX 339-4.

Nowak, M. A.; Wilms, J.; Dove, J. B.; Fender, R. P.

1999-01-01

49

Cryogenic exciter  

DOEpatents

The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)

2012-03-13

50

Post-Glitch RXTE-PCA Observations of the Vela Pulsar  

E-print Network

We report the results of analysis of observations of the Vela Pulsar by PCA on RXTE. Our data consists of two parts. The first part contains observations at 1, 4, and 9 days after the glitch in 1996 and has 27000 sec. total exposure time. The second part of observations were performed three months after this glitch and have a total exposure time of 93000 sec. We found pulsations in both sets. The observed spectrum is a power-law with no apparent change in flux or count rate. The theoretical expectations of increase in flux due to internal heating after a glitch are smaller than the uncertainty of the observations.

M. Atakan Gurkan; Altan Baykal; M. Ali Alpar; Hakki B. Ogelman; Tod Strohmayer

2000-02-25

51

A Global Look at Reflection in Black-Hole X-ray Binaries Using RXTE  

NASA Astrophysics Data System (ADS)

Spectral reflection is ubiquitous in black-hole X-ray binaries, and is produced by the coronal hard X-ray emission illuminating the cooler accretion disk. The observed interplay between coronal and reflection spectral components provides insight into the geometry of the corona - an attribute which is presently only weakly constrained We present first results from a new campaign analyzing all RXTE PCU-2 spectra of accreting stellar-mass black holes. A simple but self-consistent treatment of disk, coronal, and reflection emission highlights changes evident in the coronal geometry between soft and hard spectral states.

Steiner, James F.; Garcia, Javier; Reis, Ruben C.; McClintock, Jeffrey E.

2014-08-01

52

XTE J1752-223 seen by RXTE in Black Hole Intermediate State  

NASA Astrophysics Data System (ADS)

The first pointed RXTE observation of a new Galactic black hole candidate XTE J1752-223 (Atel #2258) after a two month period of invisibility due to Sun constrains showed that the source has changed its spectral state from a long stable extreme hard state (Atel #2269). Both thermal and a power-law component are present in the energy spectrum. The photon index of the non-thermal part is 1.9. The variability shows a broad band-limited noise with a break at 0.5 Hz accompanied by a strong low frequency quasi-periodic oscillation (QPO) at 2.2 Hz.

Shaposhnikov, N.

2010-01-01

53

XTE J1752-223: RXTE PCA Observation shows black hole candidate  

NASA Astrophysics Data System (ADS)

On 2009-10-26 at 15:03 UT, the RXTE PCA made its first pointed observation of the newly discovered transient source XTE J1752-223 (ATels #2258, #2259, #2261, #2263, #2265, #2268). The PCA spectrum is consistent with the source being in the black hole low-hard state dominated by a power law component with photon index 1.38 +/- 0.01 with a weak black body with kT=0.83+/-0.01 keV. A prominent iron line is also seen at ~6.4 keV, with equivalent width of 95 eV.

Shaposhnikov, N.; Markwardt, C. B.; Swank, J. H.

2009-10-01

54

Using Remote Sensing Technology, Web Casts, and Participation in a Valuable Research Project to Jazz Teachers and Excite Students About Science  

NASA Astrophysics Data System (ADS)

Scientific education of primary and secondary school children has become a topic of concern in Ohio and throughout the United States. So with that in mind, how do you get students excited about learning science? One route is to inform and jazz teachers about current technology! The University of Toledo has hosted three one-week, NASA and OhioView sponsored professional development institutes entitled, Observing Earth from Space, for teachers from grades K-12 during July 2000, 2001, and 2002. Sixty-seven teachers from the Upper Midwest and Kansas with Earth Science, Social Studies, and Physics backgrounds attended. Each participant acquired new ideas, plenty of educational materials, and posters of satellite imagery. The teachers received basic training in remote sensing, global positioning systems, digital elevation models, and weather observing techniques and learned about useful remote sensing applications. This instruction was conducted through: 1) presentations given by research scientists, 2) integration of the learned content into authentic, hands-on lesson plans, and 3) participation in a learning adventure, where their students collected real-time earth science data at their respective schools while university research scientists gathered corresponding satellite imagery. The students observations were submitted via a simple Web interface: www.remotesensing.utoledo.edu. One of the very exciting platforms used to communicate with the teachers and students throughout the school year were live Web Casts sponsored by NASA Glenn Research Center. The students data have successfully assisted in the validation of cloud/snow remote sensing algorithms, and next year the students observations will include various surface temperature readings. The participation in a cutting-edge technology workshop and in an important global climate change research project, applicable in the classroom, has added another worthwhile dimension to the learning process and career awareness for both the teachers and their students.

Benko, T. M.; Czajkowski, K. P.; Struble, J.; Zhao, L.

2002-12-01

55

MULTIWAVELENGTH OBSERVATIONS OF LS I +61{sup 0} 303 WITH VERITAS, SWIFT, AND RXTE  

SciTech Connect

We present results from a long-term monitoring campaign on the TeV binary LSI +61{sup 0} 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between 2006 September and 2008 February. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8{sigma} (2006/2007) and 7.3{sigma} (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5% to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6{sigma} significance level) for TeV emission outside the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0 x10{sup -11} erg cm{sup -2} s{sup -1} over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands.

Acciari, V. A. [Department of Life and Physical Sciences, Galway-Mayo Institute of Technology, Dublin Road, Galway (Ireland); Aliu, E. [Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Arlen, T.; Chow, Y. C. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Bautista, M.; Cogan, P. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Beilicke, M.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Boettcher, M. [Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Bradbury, S. M.; Daniel, M. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Butt, Y.; Butt, Y. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cannon, A. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A. [School of Physics, National University of Ireland, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Colin, P. [Physics Department, University of Utah, Salt Lake City, UT 84112 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)], E-mail: awsmith@hep.anl.gov (and others)

2009-08-01

56

First Statistical Tests for Clumpy Tori Models: Constraints from RXTE monitoring of Seyfert AGN  

NASA Astrophysics Data System (ADS)

We present an analysis of multi-timescale variability in line-of-sight X-ray absorbing gas as a function of optical classification in a large sample of Seyfert AGN to derive the first X-ray statistical constraints for clumpy-torus models. We systematically search for discrete absorption events in the vast archive of RXTE monitoring of 55 nearby type Is and Compton-thin type IIs. We are sensitive to discrete absorption events due to clouds of full-covering, neutral/mildly ionized gas with columns >˜10^{22-25} cm^{-2} transiting the line of sight. Our results probe model parameter space complementary to that for eclipses observed with XMM-Newton, Suzaku, and Chandra. We detect 12 eclipse events in 8 objects, roughly tripling the number previously published from RXTE. Peak column densities span 4-26 × 10^{22} cm^{-2}. Event durations span hours to years. The column density profile for a cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidally sheared. We infer clouds' distances from the black hole to span 0.3 - 140 × 10^4 R_{g}. Most clouds' distances are commensurate with the outer portions of the BLR, or the inner regions of infrared-emitting dusty tori. We discuss implications for cloud distributions in the context of clumpy-torus models.

Markowitz, A.; Krumpe, M.; Nikutta, R.

2014-07-01

57

A bright thermonuclear X-ray burst simultaneously observed with Chandra and RXTE  

NASA Astrophysics Data System (ADS)

The prototypical accretion-powered millisecond pulsar SAX J1808.4-3658 was observed simultaneously with Chandra-LETGS and RXTE-PCA near the peak of a transient outburst in November 2011. A single thermonuclear (type-I) burst was detected, the brightest yet observed by Chandra from any source, and the second-brightest observed by RXTE. We found no evidence for discrete spectral features during the burst; absorption edges have been predicted to be present in such bursts, but may require a greater degree of photospheric expansion than the rather moderate expansion seen in this event (a factor of a few). These observations provide a unique data set to study an X-ray burst over a broad bandpass and at high spectral resolution (?/?? = 200-400). We find a significant excess of photons at high and low energies compared to the standard black body spectrum. This excess is well described by a 20-fold increase of the persistent flux during the burst. We speculate that this results from burst photons being scattered in the accretion disk corona. These and other recent observations of X-ray bursts point out the need for detailed theoretical modeling of the radiative and hydrodynamical interaction between thermonuclear X-ray bursts and accretion disks.

in't Zand, J. J. M.; Galloway, D. K.; Marshall, H. L.; Ballantyne, D. R.; Jonker, P. G.; Paerels, F. B. S.; Palmer, D. M.; Patruno, A.; Weinberg, N. N.

2013-05-01

58

A Year of Hands-on Science: Exciting Theme Units with More Than 100 Activities, Projects, and Experiments To Make Science Come Alive.  

ERIC Educational Resources Information Center

This book contains 18 themed teaching units with 2 themes per chapter, organized seasonally around the traditional school year. Each theme includes natural connections and hands-on science activities that correspond to what children are already observing in their world. Each chapter begins with highlights of the month and a reproducible "Science

Kepler, Lynne; Novelli, Joan, Ed.

59

1018 BioScience December 2001 / Vol. 51 No. 12 The 21st century is an exciting time for biological  

E-print Network

phenomena under investigation,particularly as time or space scales change and as underlying mechanisms of biocomplexity, the term has most frequently been associated with the recent National Science Foundation program and will most likely change dramatically as our scientific understanding of this concept grows. Despite

60

Exciter switch  

NASA Technical Reports Server (NTRS)

A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.

Mcpeak, W. L.

1975-01-01

61

Low Luminosity States of the Black Hole Candidate GX 339-4. 1; ASCA and Simultaneous Radio/RXTE Observations  

NASA Technical Reports Server (NTRS)

We discuss a series of observations of the black hole candidate GX 339-4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneous with 843 Mega Hertz and 8.3-9.1 Giga Hertz radio observations. All of these observations have (3-9 keV) flux approximately less than 10(exp-9) ergs s(exp-1) CM(exp -2). The ASCA data show evidence for an approximately 6.4 keV Fe line with equivalent width approximately 40 eV, as well as evidence for a soft excess that is well-modeled by a power law plus a multicolor blackbody spectrum with peak temperature approximately equals 150-200 eV. The RXTE data sets also show evidence of an Fe line with equivalent widths approximately equal to 20-1OO eV. Reflection models show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. 'Sphere+disk' Comptonization models and Advection Dominated Accretion Flow (ADAF) models also provide reasonable descriptions of the RXTE data. The former models yield coronal temperatures in the range 20-50 keV and optical depths of r approximately equal to 3. The model fits to the X-ray data, however, do not simultaneously explain the observed radio properties. The most likely source of the radio flux is synchrotron emission from an extended outflow of extent greater than O(10 (exp7) GM/c2).

Wilms, Joern; Nowak, Michael A.; Dove, James B.; Fender, Robert P.; DiMatteo, Tiziana

1998-01-01

62

employment opportunities in exciting career paths  

E-print Network

processing and safe handling of all types of food. R&D Scientific Technical Education Sales & Marketing in exciting career paths Food Science Cerificate for BSc graduates Food Science Cerificate for BSc graduates. Because food science is a multidisciplinary applied science, a food science education provides a broad

Barthelat, Francois

63

A DOUBLE-PEAKED OUTBURST OF A 0535+26 OBSERVED WITH INTEGRAL, RXTE, AND SUZAKU  

SciTech Connect

The Be/X-ray binary A 0535+26 showed a normal (type I) outburst in 2009 August. It is the fourth in a series of normal outbursts associated with the periastron, but is unusual because it presented a double-peaked light curve. The two peaks reached a flux of {approx}450 mCrab in the 15-50 keV range. We present results of the timing and spectral analysis of INTEGRAL, RXTE, and Suzaku observations of the outburst. The energy-dependent pulse profiles and their evolution during the outburst are studied. No significant differences with respect to other normal outbursts are observed. The centroid energy of the fundamental cyclotron line shows no significant variation during the outburst. A spectral hardening with increasing luminosity is observed. We conclude that the source is accreting in the sub-critical regime. We discuss possible explanations for the double-peaked outburst.

Caballero, I. [Laboratoire AIM, CEA/IRFU, CNRS/INSU, Universite Paris Diderot, CEA DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Pottschmidt, K.; Marcu, D. M. [Center for Space Science and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Barragan, L.; Wilms, J.; Kreykenbohm, I. [Dr. Karl Remeis-Sternwarte and ECAP, FAU Erlangen-Nuremberg, Sternwartstr. 7, D-96049 Bamberg (Germany); Ferrigno, C. [ISDC Data Centre for Astrophysics, University of Geneva, Chemin d'Ecogia 16, CH-1290 Versoix (Switzerland); Klochkov, D.; Suchy, S.; Santangelo, A.; Staubert, R. [Institut fuer Astronomie und Astrophysik, Sand 1, D-72076 Tuebingen (Germany); Zurita Heras, J. A. [Francois Arago Centre, APC (UMR 7164 Universite Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris), 13 rue Watt, F-75205 Paris Cedex 13 (France); Kretschmar, P. [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, Villanueva de la Canada, E-28080 Madrid (Spain); Fuerst, F. [Space Radiation Lab, California Institute of Technology, MC 290-17 Cahill, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Rothschild, R. [Center for Astrophysics and Space Science, UCSD, La Jolla, CA 92093 (United States); Finger, M. H. [National Space Science and Technology Center, 320 Sparkman Drive NW, Huntsville, AL 35805 (United States); Camero-Arranz, A. [Institut de Ciencies de l'Espai (IEEC-CSIC), Campus UAB, Fac. de Ciencies, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain); Makishima, K. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Enoto, T. [Cosmic Radiation Laboratory, RIKEN, 2-1, Hirosawa, Wako City, Saitama 351-0198 (Japan); Iwakiri, W., E-mail: isabel.caballero@cea.fr [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570 (Japan); and others

2013-02-20

64

A study of RXTE and BeppoSAX observations of Cyg X-3  

E-print Network

We present an analysis of Cyg X-3 data from RXTE/PCA,HEXTE and ASM, supplemented by a selected spectrum from BeppoSAX. We fit the PCA/HEXTE spectra from 1996-2000 by a model including hybrid Comptonization, reflection and absorption, and classify them into hard, intermediate and soft states. Apart from the very strong absorption in Cyg X-3, the spectra resemble those of GRS 1915+105. The soft and intermediate state spectra require the presence of nonthermal Comptonizing electrons. We then study the radiative processes at soft X-rays with a hard-state spectrum from BeppoSAX modeled including emission from a photoionized plasma.

A. Szostek; A. A. Zdziarski

2004-01-14

65

RXTE Observations of A1744-361: Correlated Spectral and Timing Behavior  

NASA Technical Reports Server (NTRS)

We analyze Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) data of the transient low mass X-ray binary (LMXB) system A1744-361. We explore the X-ray intensity and spectral evolution of the source, perform timing analysis, and find that A1744-361 is a weak LMXB, that shows atoll behavior at high intensity states. The color-color diagram indicates that this LMXB was observed in a low intensity spectrally hard (low-hard) state and in a high intensity banana state. The low-hard state shows a horizontal pattern in the color-color diagram, and the previously reported dipper QPO appears only during this state. We also perform energy spectral analyses, and report the first detection of broad iron emission line and iron absorption edge from A1744-361.

Bhattacharyya, Sudip; Strohmayer, Tod E.; Swank, Jean H.; Markwardt, Craig B.

2007-01-01

66

A Simple Method to Improve the Quality of RXTE PCA Spectra  

NASA Astrophysics Data System (ADS)

We fitted at once all of the several hundred RXTE PCA spectra of the Crab to a simple power-law model; the total number of counts in the composite spectrum is >10^9. We then used the spectrum of fit residuals (data/model) to correct large samples of spectra of G 339-4, H1743-322, and XTE J1550-564. The correction improved the quality of all the fits, and the improvement was dramatic for spectra with >10^7 counts. The Crab residual spectrum is somewhat different for each of the five PCA detectors, but it was relatively stable during the course of the 16-year mission. We provide public software that automates the process of applying the correction to PCA data and recommend that the correction be applied to all spectra with >10^6 counts.

Garcia, Javier; McClintock, Jeffrey E.; Steiner, James F.; Remillard, Ronald A.; Grinberg, Victoria

2014-06-01

67

The Broadband Continuum Spectrum of Magnetar Bursts from Swift and RXTE  

NASA Astrophysics Data System (ADS)

We studied a large number of SGR bursts with Swift and RXTE to determine the best fit continuum model in the broad range of 2-350 keV. Using 10 trial models, we find acceptable fits with single component Optically thin thermal Bremsstarahlung, Cutoff Power-law, and simple Power-law models that rule out the need for a second component. We present the global spectral properties of the bursts and investigation spectral-temporal correlations. (*) This contribution presents results from students projects carried out during the 8th COSPAR Capacity Building Workshop on Space Astrophysics with NASA & ESA Missions: Swift, Chandra & XMM Newton (Jan. 20-Feb. 2, 2008; Alexandria, Egypt; http://cais.cu.edu.eg/astro)

Ibrahim, Alaa

68

Peculiar Outburst of A 0535+26 Observed with INTEGRAL, RXTE and Suzaku  

NASA Technical Reports Server (NTRS)

A normal outburst of the Be/X-ray binary system A0535+26 has taken place in August 2009. It is the fourth in a series of normal outbursts that have occurred around the periastron passage of the source. but is unusual by starting at an earlier orbital phase and by presenting a peculiar double-peaked light curve. A first "flare" (lasting about 9 days from M.ID 55043 on) reached a flux of 440 mCrab. The flux then decreased to less than 220 mCrab. and increased again reaching 440 mCrab around the periastron at MJD 55057. Target of Opportunity observations have been performed with INTEGRAL. RXTE and Suzaku. First results of these observations are presented. with special emphasis on the cyclotron lines present in the X-ray spectrum of the source. as well as in the pulse period and energy dependent pulse profiles of the source

Caballero, I.; Pottschmidt, K.; Barragan, L.; Ferrigno, C.; Kretschmar, P.; Suchy, S.; Wilms, J.; Santangelo, A.; Kreykenbohm, I.; Rothschild, R.; Klochkov, D.; Staubert, R.; Finger, M. H.; Camero-Arranz, A.; Makishima, K.; Enoto, T.

2009-01-01

69

Excite Travel  

NSDL National Science Digital Library

Excite Travel is one of the most comprehensive international guides to communities around the world. Excite Travel provides easy and timely access to information on travel, entertainment, and local business, plus government and community services for all regions of the world.

1998-01-01

70

2013-2014 SciTech Executive Experience The Office of Science Education Outreach (OSEO), Health Sciences, is pleased to announce an exciting  

E-print Network

Street and Fifth Avenue, opened in September 2009. This unique science and technology school serves-school/executive- experience to download the Project Proposal form. 2. Submit your proposal via Arthur Jackson at arthurj to download the Executive Experience Project Partner Guide (www.howscienceworks.pitt.edu/students-k-12/high

Sibille, Etienne

71

Exciting Pools  

ERIC Educational Resources Information Center

Advocates the creation of swimming pool oscillations as part of a general investigation of mechanical oscillations. Presents the equations, procedure for deriving the slosh modes, and methods of period estimation for exciting swimming pool oscillations. (GS)

Wright, Bradford L.

1975-01-01

72

The Crab Pulsar Observed by RXTE: Monitoring the X-Ray to Radio Delay for 16 Years  

NASA Technical Reports Server (NTRS)

In 2004 we published the results of monitoring the Crab Pulsar by RXTE. At that time we determined that the primary pulse of the pulsar at X-ray energies precedes its radio counterpart by about 0.01 period in phase or approximately 330 micro seconds. However, we could not establish unambiguously whether the delay is in phase or due to a difference in pathlength. At this time we have twice the time baseline we had in 2004 and we present the same analysis, but now over a period of 16 years, which will represent almost the full mission and the best that will be available from RXTE. The full dataset shows that the phase delay has been decreasing faster than the pulse frequency over the 16 year baseline and that there are variations in the delay on a variety of timescales.

Rots, Arnold; Jahoda, Keith

2012-01-01

73

Focus Issue: Getting Excited About Glia  

NSDL National Science Digital Library

This Focus Issue of Science Signaling complements the Science Special Issue and highlights glial cell function, development, and disease. This issue draws attention to the molecular mechanisms of drug resistance of a cancer of glial origin, and to signaling between glia and neurons. Although glia may not be excitable, they are clearly an exciting group of cells.

Elizabeth M. Adler (American Association for the Advancement of Science;Science Signaling REV)

2010-11-09

74

International Observe the Moon Night - An Opportunity to Participate in the Year of the Solar System While Sharing the Excitement of Lunar Science and Exploration with the Public  

NASA Astrophysics Data System (ADS)

International Observe the Moon Night (InOMN) is a multi-nation effort to share the excitement of recent lunar missions and new science results with education communities, amateur astronomers, space enthusiasts, and the general public. It is also intended to encourage the world to experience the thrill of observing Earth’s closest neighbor. The inaugural InOMN took place on September 18, 2010. People in over 26 countries gathered together in groups big and small to learn about the Moon through presentations by scientists, astronomers, and engineers; participate in hands-on activities; and observe the Moon through telescopes, binoculars, and the naked eye. Next year’s InOMN will take place on October 8, 2011 during the Year of the Solar System (YSS). The October 2011 YSS theme will be “Moons/Rings Across the Solar System.” InOMN is perfectly suited as an event that any museum, science center, planetarium, university, school, or other group can implement to celebrate YSS. The InOMN Coordinating Committee has developed a variety of resources and materials to make it easy to host an InOMN event of any size. Interested groups are encouraged to utilize the InOMN website (observethemoonnight.org) in planning their InOMN event for 2011/YSS. The website contains links to Moon resources, educational activities, suggestions for hosting an event, free downloads of logos and flyers for advertising an event, and contests. New for 2011 will be a discussion forum for event hosts to share their plans, tips, and experiences. Together, YSS and InOMN will enable the public to maintain its curiosity about the Moon and to gain a better understanding of the Moon’s formation, evolution, and place in the night sky.

Bleacher, L.; Daou, D.; Day, B. H.; Hsu, B. C.; Jones, A. P.; Mitchell, B.; Shaner, A. J.; Shipp, S. S.

2010-12-01

75

RXTE observations of strongly absorbed sources IGR J16318-4848 and IGR J16358-4726  

E-print Network

Results of analysis of RXTE observations of strongly absorbed X-ray sources IGR J16318-4848 and IGR J16358-4726 are presented. Careful subtraction of Galactic ridge emission contribution to the observed spectra of RXTE/PCA allowed us to obtain the spectra of the sources in 3-25 keV energy band. Spectra of the sources cold be well described by a power law with photoabsorption. It is shown that the value of absorption column in the case of RXTE observation of IGR J16318-4848 performed on March 14.1, 2003 is somewhat higher that that obtained by XMM observatory on Feb 10.7 2003. This could imply that the source has variable absorption, presumably connected with an orbital phase of the binary system. It is noted, that all three X-ray sources, discovered by INTEGRAL observatory in the sky region of (l,b)~(336,0) (IGR J16318-4848, IGR J16320-4751 and IGR J16358-4726) have large intrinsic photoabsorption and could be high mass X-ray binaries. This hypothesis has indirect support from the fact that their are located close to the Norma spiral arm tangent, i.e. in the region of enhanced concentrations of young massive stars. If they are reside within this spiral arm some rough estimation of the sources distance could be made -- D~6-8 kpc.

M. Revnivtsev

2003-04-20

76

LMC X-1 and LMC X-3 as Seen by RXTE  

NASA Technical Reports Server (NTRS)

LMC X-1 and LMC X-3 are the only two black holes that are consistently seen in the soft X-ray state. We present the results from the spectral and temporal analysis of a long (150 ksec) observation of these two objects. The spectra can be well described by a disk black body plus a high energy power-law, which extends to at least 50keV. Starting in December 1996 we have also monitored these objects with RXTE in about three to four week intervals. We present the evolution of the spectral parameters of the sources from the first twenty pointings. LMC X-1 has a very stable spectrum and does not exhibit any large scale variability. On the other hand, the appearance of LMC X-3 changes considerably over its 200d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

1998-01-01

77

Diagnostics of the candidate to the black hole SS433 with the RXTE  

E-print Network

We present our analysis of the extensive monitoring of SS433 by the RXTE observatory collected over the period 1996-2005. The difference between energy spectra taken at different precessional and orbital phases shows the presence of strong photoabsorption (N_H>10^{23}cm^{-2}) near the optical star, probably due to its powerful, dense wind. Therefore the size of the secondary deduced from analysis of X-ray orbital eclipses might be significantly larger than its Roche lobe size, which must be taken into account when evaluating the mass ratio from analysis of X-ray eclipses. Assuming that a precessing accretion disk is geometrically thick, we recover the temperature profile in the X-ray emitting jet that best fits the observed precessional variations in the X-ray emission temperature. The hottest visible part of the X-ray jet is located at a distance of l_0/a~0.06-0.09, or ~2-3*10^{11}cm from the central compact object, and has a temperature of about T_{max}~30 keV. We discovered appreciable orbital X-ray eclips...

Filippova, E; Fabrika, S; Postnov, K; Seifina, E

2006-01-01

78

An Empirical Method for Improving the Quality of RXTE PCA Spectra  

NASA Astrophysics Data System (ADS)

We fitted all of the several hundred RXTE PCA spectra of the Crab individually to a simple power-law model; the total number of counts in the composite spectrum is >109. We then used the spectrum of residuals to derive a calibration tool, called pcacorr, that we apply to large samples of spectra for GX 339-4, H1743-322, and XTE J1550-564. Application of the tool improved the quality of all the fits, and the improvement is dramatic for spectra with >~ 107 counts. The Crab residual spectrum is somewhat different for each of the five Proportional Counter Array (PCA) detectors, but it was relatively stable over the course of the mission. We recommend that pcacorr be routinely applied to spectra with >~ 106 counts and that one include a systematic error of 0.1%, rather than the 0.5-1% value that has customarily been used. We expect that application of the tool will result in an increase in sensitivity of the PCA to faint spectral features by up to an order of magnitude.

García, Javier A.; McClintock, Jeffrey E.; Steiner, James F.; Remillard, Ronald A.; Grinberg, Victoria

2014-10-01

79

Excited Insects  

E-print Network

but not killing them doesn't actually count as true celebration. Now, China. There's a country that knows how to make a bug feel good. Bugs have their very own holiday in the Chinese calendar. It's called the Feast of the Excited Insects and it falls on March 5th...

Hacker, Randi

2011-04-06

80

Excited Delirium  

PubMed Central

Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

2011-01-01

81

Excited Delirium  

Microsoft Academic Search

Excited delirium accounts for 1% of our EDP (emotionally disturbed persons) cases and 99% of our headaches.” This comment,\\u000a made some years ago at a New York City conference of police chiefs captures the managerial and legal concerns of this entity.\\u000a Police managers are concerned because their officers are suddenly confronted with psychotic, violent persons, which sets into\\u000a motion an

Charles V. Wetli

82

Excited baryons  

SciTech Connect

The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

Mukhopadhyay, N.C.

1986-01-01

83

Twelve and a Half Years of Observations of Centaurus A with RXTE  

NASA Technical Reports Server (NTRS)

The Rossi X-ray Timing Explorer has observed the nearest radio galaxy, Centaurus A, in 13 intervals from 1996 August to 2009 February over the 3 - 200 keV band. Spectra accumulated over the 13 intervals were well described with an absorbed power law and an iron line. Cut-off power laws and Compton reflection from cold matter did not provide a better description. For the 2009 January observation we set a lower limit on the cutoff energy at over 2 MeV. The power spectral density function was generated from RXTE/ASM and PCA data as well as an XMM-Newton long look, and clear evidence for a break at 18(+18/-7) days (68% conf.) was seen. Given Cen A's high black hole mass and very low value of L(sub x)/L(sub Edd), the break was a factor of 17+/-9 times higher than the break frequency predicted by the McHardy and coworkers relation, which was empirically derived for a sample of objects, which are radio-quiet and accreting at relatively high values of L(sub bol)/L(sub Edd). We have interpreted our observations in the context of a clumpy molecular torus. The variability characteristics and the broadband spectral energy distribution, when compared to Seyferts, imply that the bright hard X-ray continuum emission may originate at the base of the jet, yet from behind the absorbing line of sight material, in contrast to what is commonly observed from blazars.

Rothschild, R. E.; Markowitz, A.; Rivers, L.; Suchy, S.; Pottschmidt, K.; Kadler, M.; Mueller, C.; Wilms, J.

2011-01-01

84

Diagnostics of the black hole candidate SS433 with the RXTE  

E-print Network

We present our analysis of the extensive monitoring of SS433 by the RXTE observatory collected over the period 1996-2005. The difference between energy spectra taken at different precessional and orbital phases shows the presence of strong photoabsorption (N_H>10^{23}cm^{-2}) near the optical star, probably due to its powerful, dense wind. Therefore the size of the secondary deduced from analysis of X-ray orbital eclipses might be significantly larger than its Roche lobe size, which must be taken into account when evaluating the mass ratio from analysis of X-ray eclipses. Assuming that a precessing accretion disk is geometrically thick, we recover the temperature profile in the X-ray emitting jet that best fits the observed precessional variations in the X-ray emission temperature. The hottest visible part of the X-ray jet is located at a distance of l_0/a~0.06-0.09, or ~2-3*10^{11}cm from the central compact object, and has a temperature of about T_{max}~30 keV. We discovered appreciable orbital X-ray eclipses at the ``crossover'' precessional phases (jets are in the plane of the sky, disk is edge-on), which under model assumptions put a lower limit on the size of the optical component R/a>0.5 and an upper limit on a mass ratio of binary companions q=M_x/M_{opt}X-ray opaque size of the star is not larger than 1.2R_{Roche, secondary}.

E. Filippova; M. Revnivtsev; S. Fabrika; K. Postnov; E. Seifina

2006-09-13

85

RXTE Observations of the Seyfert 2 Galaxy MrK 348  

NASA Technical Reports Server (NTRS)

We present RXTE monitoring observations of the Seyfert 2 galaxy Mrk 348 spanning a 6 month period. The time-averaged spectrum in the 3-20 keV band shows many features characteristic of a Compton-thin Seyfert 2 galaxy, namely a hard underlying power-law continuum (Gamma approximately equal 1.8) with heavy soft X-ray absorption (N(sub H) approximately 10(exp 23)/sq cm) plus measurable iron K.alpha emission (equivalent width approximately 100 eV) and, at high energy, evidence for a reflection component (R approximately < 1). During the first half of the monitoring period the X-ray continuum flux from Mrk 348 remained relatively steady. However this was followed by a significant brightening of the source (by roughly a factor of 4) with the fastest change corresponding to a doubling of its X-ray flux on a timescale of about 20 days. The flux increase was accompanied by a marked softening of X-ray spectrum most likely attributable to a factor approximately 3 decline in the intrinsic line-of-sight column density. In contrast the iron K.alpha line and the reflection components showed no evidence of variability. These observations suggest a scenario in which the central X-ray source is surrounded by a patchy distribution of absorbing material located within about a light-week of the nucleus of Mrk 348. The random movement of individual clouds within the absorbing screen, across our line of sight, produces substantial temporal variations in the measured column density on timescales of weeks to months and gives rise to the observed X-ray spectral variability. However, as viewed from the nucleus the global coverage and typical thickness of the cloud layer remains relatively constant.

Smith, David A.; Georgantopoulos, Ioannis; Warwick, Robert S.

2000-01-01

86

INTEGRAL and RXTE/ASM Observations on IGR J17098-3628  

NASA Astrophysics Data System (ADS)

To further probe the possible nature of the unidentified source IGR J17098-3628, we have carried out a detailed analysis of its long-term time variability, as monitored by Rossi X-ray Timing Explorer/All Sky Monitor (RXTE/ASM), and of its hard X-ray properties, as observed by the International Gamma-Ray Astrophysics Laboratory (INTEGRAL). INTEGRAL has monitored this sky region for years, and significantly detected IGR J17098-3628 only when the source was in its dubbed active state. In particular, at ?20keV, Imager on Board of the INTEGRAL Satellite/INTEGRAL Soft Gamma-Ray Imager (IBIS/ISGRI) caught an outburst in 2005 March, lasting for ˜5 d with a detection significance of 73? (20--40 keV) and with emission at <200 keV. ASM observations have revealed that the outburst of the soft X-ray lightcurve is similar to that detected by INTEGRAL; however the peak of the soft X-ray lightcurve lags behind, or is preceded by, the hard X-ray (>20 keV) outburst by ˜2 d. This resembles the behavior of X-ray novae like XN 1124-683, and hence further suggests a Low-Mass X-ray Binary (LMXB) nature for IGR J17098-3628. While the quality of the ASM data prevents us from drawing any definite conclusions, these discoveries are important clues that, coupled with future observations, will help us to resolve the nature of IGR J17098-3628 that is unknown so far.

Chen, Yu-Peng; Zhang, Shu; Schurch, Nick; Wang, Jian-Min; Collmar, Werner; Li, Ti-Pei; Qu, Jin-Lu; Zhang, Cheng-Min

2008-10-01

87

An Expanded RXTE Survey of Long-Term X-ray Variability in Seyfert 1 Galaxies  

NASA Technical Reports Server (NTRS)

The first seven years of RXTE monitoring of Seyfert 1 active galactic nuclei have been systematically analyzed to yield five homogenous samples of 2-12 keV light curves, probing hard X-ray variability on successively longer durations from approx. 1 day to approx. 3.5 years. 2-10 keV variability on time scales of approx. 1 day, as probed by ASCA, are included. All sources exhibit stronger X-ray variability towards longer time scales, with variability amplitudes saturating at the longest time scales, but the increase is greater for relatively higher luminosity sources. The well-documented anticorrelation between variability amplitude and luminosity is confirmed on all time scales. However, anticorrelations between variability amplitude and black hole mass estimate are evident on only the shortest time scales probed. The data are consistent with the models of power spectral density (PSD) movement described in Markowitz et al. (2003) and McHardy et al. (2004), whereby Seyfert 1 galaxies variability can be described by a single, universal PSD shape whose cutoff frequency scales with black hole mass. The best-fitting scaling relations between variability time scale, black hole mass and X-ray luminosity support an average accretion rate of 2% of the Eddington limit for the sample. Nearly all sources exhibit stronger variability in the relatively soft 2-4 keV band compared to the 7-12 keV band on all time scales. Color-flux diagrams support also Seyfert 1s' softening as they brighten. There are indications that relatively less luminous or less massive sources exhibit a greater degree of spectral variability for a given increase in overall flux.

Markowitz, A.; Edelson, R.

2004-01-01

88

Results of WEBT, VLBA and RXTE monitoring of 3C 279 during 2006-2007  

E-print Network

We present radio-to-optical data taken by the WEBT, supplemented by VLBA and RXTE observations, of 3C 279. Our goal is to use this extensive database to draw inferences regarding the physics of the relativistic jet. We assemble multifrequency light curves with data from 30 ground-based observatories and the space-based instruments, along with linear polarization vs. time in the optical R band. In addition, we present a sequence of 22 images (with polarization vectors) at 43 GHz at resolution 0.15 milliarcsec, obtained with the VLBA. We analyse the light curves and polarization, as well as the spectral energy distributions at different epochs, corresponding to different brightness states. The IR-optical-UV continuum spectrum of the variable component corresponds to a power law with a constant slope of -1.6, while in the 2.4-10 keV X-ray band it varies in slope from -1.1 to -1.6. The steepest X-ray spectrum occurs at a flux minimum. During a decline in flux from maximum in late 2006, the optical and 43 GHz core polarization vectors rotate by ~300 degrees. The continuum spectrum agrees with steady injection of relativistic electrons with a power-law energy distribution of slope -3.2 that is steepened to -4.2 at high energies by radiative losses. The X-ray emission at flux minimum comes most likely from a new component that starts in an upstream section of the jet where inverse Compton scattering of seed photons from outside the jet is important. The rotation of the polarization vector implies that the jet contains a helical magnetic field that extends ~20 pc past the 43 GHz core.

V. M. Larionov; S. G. Jorstad; A. P. Marscher; C. M. Raiteri; M. Villata

2008-10-23

89

Faculty of Science Environmental Science  

E-print Network

Faculty of Science Environmental Science If you have a natural curiosity and concern about the environment, Environmental Science offers you exciting career opportunities. It applies scientific tools from.uwindsor.ca/earth #12;Environmental Science We look forward to meeting you! You will receive a solid grounding

90

XTE J1752-223: a new RXTE and Swift detected X-ray transient in the galactic center region  

NASA Astrophysics Data System (ADS)

On 2009-10-23 at 19:55 UT, RXTE discovered a new source while scanning the galactic bulge region, designated XTE J1752-223. Based on the existing PCA scan data, the best fit position is, R.A. = 268.05(16), Dec. = -22.31(4) (J2000), with estimated 95% uncertainty of the final digits shown in parentheses. The 2-10 keV flux of the source at that time was about 30 mCrab. In the past six months, no source has been detected at that position with 95% upper limit of about 1 mCrab.

Markwardt, C. B.; Swank, J. H.; Barthelmy, S. D.; Baumgartner, W. H.; Burrows, D. N.; Evans, P. A.; Holland, S. T.; Hoversten, E. A.; Page, K. L.

2009-10-01

91

Launch Excitement with Water Rockets  

ERIC Educational Resources Information Center

Explosions and fires--these are what many students are waiting for in science classes. And when they do occur, students pay attention. While we can't entertain our students with continual mayhem, we can catch their attention and cater to their desires for excitement by saying, "Let's make rockets." In this activity, students make simple, reusable…

Sanchez, Juan Carlos; Penick, John

2007-01-01

92

A decade of Rossi X-ray Timing Explorer Seyfert observations: An RXTE Seyfert spectral database  

NASA Astrophysics Data System (ADS)

With over forty years of X-ray observations, we should have a grasp on the X- ray nature of active galactic nuclei (AGN). The unification model of Antonucci and Miller (1985) offered a context for understanding observations by defining a "typical" AGN geometry, with observed spectral differences explained by line- of-sight effects. However, the emerging picture is that the central AGN is more complex than unification alone can describe. We explore the unified model with a systematic X-ray spectral study of bright Seyfert galaxies observed by the Rossi X-Ray Timing Explorer (RXTE) over its first 10 years. We develop a spectral-fit database of 821 time-resolved spectra from 39 Seyfert galaxies fitted to a model describing the effects of an X-ray power-law spectrum reprocessed and absorbed by material in the central AGN region. We observe a relationship between radio and X-ray properties for Seyfert 1s, with the spectral parameters differing between radio-loud and radio-quiet Seyfert 1s. We also find a complex relationship between the Fe K equivalent width ( EW ) and the power-law photon index (Gamma) for the Seyfert 1s, with a correlation for the radio-loud sources and an anti-correlation for the radio- quiet sources. These results can be explained if X-rays from the relativistic jet in radio-loud sources contribute significantly to the observed spectrum. We observe scatter in the EW-Gamma relationship for the Seyfert 2s, suggesting complex environments that unification alone cannot explain. We see a strong correlation between Gamma and the reflection fraction ( R ) in the Seyfert 1 and 2 samples, but modeling degeneracies are present, so this relationship cannot be trusted as instructive of the AGN physics. For the Seyfert 1 sample, we find an anticorrelation between EW and the 2 to 10 keV luminosity ( L x ), also known as the X-ray Baldwin effect. This may suggest that higher luminosity sources contain less material or may be due to a time-lag effect. We do not observe the previously reported relationship between Gamma and the ratio of L x to the Eddington luminosity.

Mattson, Barbara Jo

2008-10-01

93

RXTE and BeppoSAX Observations of MCG-5-23-16: Reflection From Distant Cold Material  

NASA Technical Reports Server (NTRS)

We examine the spectral variability of the Seyfert 1.9 galaxy MCG-5-23-16 using RXTE and BeppoSAX observations spanning 2 years from April 1996 to April 1998. During the first year the X-ray source brightens by a factor of approximately 25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond measurably to the continuum increase. However, by the end of the second year during the BeppoSAX epoch the X-ray source has faded again. This time, the reprocessed emission has also faded, indicating that the reprocessed flux has responded to the continuum. If these effects are caused by time delays due to the distance between the X-ray source and the reprocessing region, we derive a light crossing time of between approximately 1 light day and approximately 1.5 light years. This corresponds to a distance of 0.001 pc to 0.55 pc, which implies that the reprocessed emission originates between 3 x 10(exp 15) cm and 1.6 x 10(exp l8) cm from the X-ray source. In other words, the reprocessing in MCG-5-23-16 is not dominated by the inner regions of a standard accretion disk.

Mattson, B. J.; Weaver, K. A.

2003-01-01

94

RXTE Observations of the 1A 1118-61 in an Outburst, and the Discovery of a Cyclotron Line  

NASA Technical Reports Server (NTRS)

We present the analysis of RXTE monitoring data obtained during the January 2009 outburst of the hard X-ray transient IA 1118-61. Using these observations the broadband (3.5-120 keV) spectrum of the source was measured for the first time ever. We have found that the broadband continuum spectrum of the source is similar to other accreting pulsars and is well described by several conventionally used phenomenological models. We have discovered that regardless of the applied continuum model, a prominent broad absorption feature at approx. 55 keV is observed. We interpret this feature as a Cyclotron Resonance Scattering Feature (CRSF). The observed CRSF energy is one of the highest known and corresponds to a magnetic field of B approx. 4.8 x 10(exp 12) G in the scattering region. Furthermore, our data suggests an iron emission line presence, which was not reported previously for lA 1118-61 as well. Timing properties of the source, including a strong spin-up, were found to be similar to those observed by CGRO/BATSE during the previous outburst, however the broadband capabilities of RXTE reveal a more complicated energy dependency of the pulse-profile.

Doroshenko, V.; Suchy, S.; Santangelo, A; Staubert, R.; Kreykenbohm, I.; Rothschild, R.; Pottschmidt, K.; Wilms, J.

2010-01-01

95

Chandra and RXTE Observations of 1E 1547.0-5408: Comparing the 2008 and 2009 Outbursts  

NASA Technical Reports Server (NTRS)

We present results from observations of the magnetar 1E 1547.0-5408 (SGR J1550-5418) taken with the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer (RXTE) following the source s outbursts in 2008 October and 2009 January. During the time span of the Chandra observations, which covers days 4 through 23 and days 2 through 16 after the 2008 and 2009 events, respectively, the source spectral shape over the Chandraband remained stable, while the pulsar s spindown rate in the same span in 2008 increased by a factor of 2.2 as measured by RXTE. This suggests decoupling between the source s spin-down and radiative changes, hence between the spin-down-inferred magnetic field strength and that inferred spectrally. The lack of spectral variation during flux decay is surprising for models of magnetar outbursts. We also found a strong anti-correlation between the phase-averaged flux and the pulsed fraction in the 2008 and 2009 Chandra data, but not in the pre-2008 measurements. We discuss these results in the context of the magnetar model.

Ng, C.-Y.; Kaspi, V. M.; Dib, R.; Olausen, S. A.; Scholz, P.; Guever, T.; Oezel, F.; Gavril, F. P.; Woods, P. M.

2010-01-01

96

NASA and Mary J. Blige Encourage Exciting Careers For Women  

NASA Video Gallery

NASA is collaborating with award-winning recording artist Mary J. Blige to encourage young women to pursue exciting experiences and career choices through studying science, technology, engineering ...

97

Disk-dominated States of 4U 1957+11: Chandra, XMM-Newton, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole  

E-print Network

We present simultaneous Chandra High-Energy Transmission Gratings (HETG) and Rossi X-ray Timing Explorer (RXTE) observations of a "soft state" of the black hole candidate 4U 1957+11. These spectra, having limited hard X-ray ...

Nowak, Michael A.

98

The use of magnetic field data to estimate attitude and trajectory for the Rossi X-Ray Timing Explorer (RXTE)  

NASA Technical Reports Server (NTRS)

A single augmented extended Kalman filter (EKF) is proposed for the simultaneous and autonomous estimation of spacecraft trajectory and attitude with data from the Rossi X-ray timing explorer (RXTE) magnetometer and gyro-measured body rates. The derivation of the EKF is outlined, including the measurement update and the propagation. The results from a 12 hour span of data are processed and compared with operational estimations computed at the NASA Goddard Space Flight Center (MD). The filter was found to be able to overcome very large initial errors and converge to steady state averages of less than 30 km in position, 0.05 km/s in velocity and 3 deg in attitude.

Deutschmann, Julie; Bar-Itzhack, Itzhack

1997-01-01

99

Swift and RXTE Observations of the Black Hole Transient GX 339-4 in the Hard State between Outbursts  

NASA Astrophysics Data System (ADS)

We use simultaneous Swift and RXTE observations of the black hole binary GX 339-4 to measure the inner radius of its accretion disk in the hard state down to 0.4% L Edd via modeling of the thermal disk emission and the relativistically broadened iron line. For the luminosity range covered in this work, our results rule out a significantly truncated disk at 100-1000 Rg as predicted by the advection-dominated accretion flow paradigm. The measurements depend strongly on the assumed emission geometry, with most results providing no clear picture of radius evolution. If the inclination is constrained to roughly 20°, however, the measurements based on the thermal disk emission suggest a mildly receding disk at a luminosity of 0.4% L Edd. The iron abundance varies between ~1 and 2 solar abundances, with the i = 20° results indicating a negative correlation with luminosity, though this is likely due to a change in disk illumination geometry.

Allured, Ryan; Tomsick, John A.; Kaaret, Philip; Yamaoka, Kazutaka

2013-09-01

100

Comprehensive Analysis of RXTE Data from Cyg X-1. Spectral Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations  

NASA Technical Reports Server (NTRS)

We present timing and spectral analysis of approx. 2.2 Ms of Rossi X-ray Time Explorer (RXTE) archival data from Cyg X-1. Using the generic Comptonization model we reveal that the spectrum of Cyg X-1 consists of three components: a thermal seed photon spectrum, a Comptonized part of the seed photon spectrum and the iron line. We find a strong correlation between 0.1-20 Hz frequencies of quasiperiodic oscillations (QPOs) and the spectral power-law index. Presence of two spectral phases (states) are clearly seen in the data when the spectral indices saturate at low and high values of QPO frequencies. This saturation effect was discovered earlier in a number of black hole candidate (BHC) sources and now we strongly confirm this phenomenon in Cyg X-1. In the soft state this index- QPO frequency correlation shows a saturation of the photon index Gamma approx. 2.1 at high values of the low frequency upsilon(sub L). The saturation level of Gamma approx. 2.1 is the lowest value found yet in BHCs. The bolometric luminosity does not show clear correlation with the index. We also show that Fe K(sub alpha) emission line strength (equivalent width, EW) correlates with the QPO frequency. EW increases from 200 eV in the low/hard state to 1.5 keV in the high/soft state. The revealed observational correlations allow us to propose a scenario for the spectral transition and iron line formation which occur in BHC sources. We also present the spectral state (the power-law index) evolution for eight years of Cyg X-1 observations by RXTE.

Shaposhnikov, Nickolai; Titarchuk, Lev

2006-01-01

101

INTEGRAL, Swift, and RXTE observations of the 518 Hz accreting transient pulsar Swift J1749.4-2807  

NASA Astrophysics Data System (ADS)

Context. The burst-only source Swift J1749.4-2807 was discovered in a high X-ray-active state, during an INTEGRAL observations of the Galactic bulge on 2010 April 10. Pulsations at 518 Hz were discovered in the RXTE data, confirming previous suggestions of possible associations between burst-only sources and accreting millisecond X-ray pulsars. The subsequent discovery of X-ray eclipses made Swift J1749.4-2807 the first eclipsing accreting millisecond X-ray pulsar. Aims: We obtain additional information on Swift J1749.4-2807 and other burst-only sources. Methods: We report on the results of a monitoring campaign on the source, carried out for about two weeks with the Swift, INTEGRAL, and RXTE satellites. Results: The observations showed that the X-ray spectrum (energy range 0.5-40 keV) of Swift J1749.4-2807 during the entire event was accurately modeled by an absorbed power-law model (NH ? 3 × 1022 cm-2, ? ? 1.7). X-ray eclipses were also detected in the Swift data and provides a clear evidence of a dust-scattering halo located along the line of sight to the source. Only one type-I X-ray burst was observed throughout the two-weeks long monitoring. The X-ray flux of Swift J1749.4-2807 decayed below the detection threshold of Swift /XRT about 11 days after the discovery, in a exponential fashion (e-folding time of ? = 12+7-3 days). Conclusions: We compare the properties of the outburst observed from Swift J1749.4-2807 with those of the previously known millisecond X-ray pulsars and other transient low mass X-ray binaries.

Ferrigno, C.; Bozzo, E.; Falanga, M.; Stella, L.; Campana, S.; Belloni, T.; Israel, G. L.; Pavan, L.; Kuulkers, E.; Papitto, A.

2011-01-01

102

Materials modification by electronic excitation  

NASA Astrophysics Data System (ADS)

Electronic excitation by lasers or electron beams can modify the properties of materials. The changes are not just due to heat, nor do they result from the well-known collision dynamics of much radiation damage. Everyday examples of modification by electronic excitation include photography, and photochromics (such as sunglasses) which change colour. In the last few years it has become clear that excitation can offer novel types of modification, with better-controlled changes. The field has evolved through a mix of basic science, of new laser and electron beam tools, and of new needs from microelectronics, photonics and nanotechnology. Underlying this development are some common themes which integrate the basic science and its applications. These include especially the ideas of energy localisation and charge localisation. There are detailed comparisons of experiment and theory for halides, but there is a wealth of information for other materials. From this, we identify ways to connect understanding to technological needs, like selective removal of material, controlled changes, altering the balance between process steps, and possibilities of quantum control. The field is reviewed in full in our recent book [N. Itoh, A.M. Stoneham, Materials Modification by Electronic Excitation, Cambridge University Press, Cambridge, 2000].

Stoneham, A. M.; Itoh, Noriaki

2000-12-01

103

Science.  

ERIC Educational Resources Information Center

This document contains the following papers on science instruction and technology: "A 3-D Journey in Space: A New Visual Cognitive Adventure" (Yoav Yair, Rachel Mintz, and Shai Litvak); "Using Collaborative Inquiry and Interactive Technologies in an Environmental Science Project for Middle School Teachers: A Description and Analysis" (Patricia…

Roach, Linda E., Ed.

104

Defining the High-Energy Variability Characteristics of NLS1S: Coordinated Rxte\\/euve\\/asca\\/chandra Monitoring of Ton S180  

Microsoft Academic Search

We request RXTE observe the bright NLS1 Ton S180, 1 ks\\/orbit for 34 days (512 orbits) to complete co-ordinated monitoring with EUVE, Chandra & ASCA. Temporal cross-correlation with EUVE & ASCA will provide a critical test of the model that the X-rays are produced by Compton upscattering of EUV photons. Combining with continuous Chandra data will define the fluctuation PDS

Tracey Turner

2000-01-01

105

TeV and X-ray Monitoring of LS I +61 303 With VERITAS, Swift, and RXTE  

E-print Network

Between September 2006 and February 2007, the galactic binary LS I +61 303 was monitored in the TeV band with the VERITAS array of imaging Cherenkov telescopes. These observations confirm LS I +61 303 as a variable TeV gamma-ray source, with emission peaking between orbital phase 0.6 and 0.7. During this observational period, monitoring in the X-ray regime was also carried out using both the RXTE and Swift detectors, which offered complementary coverage of the source. Outbursts in the 0.2-10 keV band were observed by both satellites at close to the same orbital phase as the TeV peak during the 2 orbital cycles covered simultaneously in both bands. While this source has been extensively studied in the X-ray band in the past, this is the first observational campaign to utilize contemporaneous X-ray and TeV data on LS I +61 303.

VERITAS Collaboration; A. Smith

2007-09-27

106

The Discovery Outburst of the X-Ray Transient IGR J17497-2821 Observed with RXTE and ATCA  

NASA Technical Reports Server (NTRS)

We report the results of a series of RXTE and ATCA observations of the recently discovered X-ray transient IGR J17497-2821. Our 3-200 keV PCA+HEXTE spectral analysis shows very little variations over a period of approx.10 days around the maximum of the outburst. IGR J17497-2821 is found in a typical low-hard state (LHS) of X-ray binaries (XRBs), well represented by an absorbed Comptonized spectrum with an iron edge at about 7 keV. The high value of the absorption (approx.4 x 10(exp 22/sq cm suggests that the source is located at a large distance, either close to the Galactic center or beyond. The timing analysis shows no particular features, while the shape of the power density spectra is also typical of the LHS of XRBs, with apprrox.36% rms variability. No radio counterpart is found down to a limit of 0.21 mJy at 4.80 and 8.64 GHz. Although the position of IGR J17497-2821 in the radio to X-ray flux diagram is well below the correlation usually observed in the LHS of black holes, the comparison of its X-ray properties with those of other sources leads us to suggest that it is a black hole candidate.

Rodriquez, Jerome; Bel, Marion Cadolle; Tomsick, John A.; Corbel, Stephane; Brocksopp, Catherine; Paizis, Ada; Shaw, Simon E.; Bodaghee, Arash

2007-01-01

107

Monitoring the Violent Activity from the Inner Accretion Disk of the Seyfert 1.9 Galaxy NGC 2992 with RXTE  

NASA Technical Reports Server (NTRS)

We present the results of a one year monitoring campaign of the Seyfert 1.9 galaxy NGC 2992 with RXTE. Historically, the source has been shown to vary dramatically in 2-10 keV flux over timescales of years and was thought to be slowly transitioning between periods of quiescence and active accretion. Our results show that in one year the source continuum flux covered almost the entire historical range, making it unlikely that the low-luminosity states correspond to the accretion mechanism switching off. During flaring episodes we found that a highly redshifted Fe K line appears, implying that the violent activity is occurring in the inner accretion disk, within 100 gravitational radii of the central black hole. We also found that the Compton y parameter for the X-ray continuum remained approximately constant during the large amplitude variability. These observations make NGC 2992 well-suited for future multi-waveband monitoring, as a test-bed for constraining accretion models.

Mruphy, Kendrah D.; Yaqoob, Tahir; Terashima, Yuichi

2007-01-01

108

RXTE and BeppoSAX Observations of the Transient X-ray Pulsar XTE J 18591+083  

NASA Technical Reports Server (NTRS)

We present observations of the 9.8 s X-ray pulsar XTE J159+083 made with the All-Sky Monitor (ASM) and Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer (RXTE), and the Wide Field Cameras (WFC) on board BeppoSAX. The ASM data cover a 12 year time interval and show that an extended outburst occurred between approximately MJD50, 250, and 50, 460 (1996 June 16 to 1997 January 12). The ASM data excluding this outburst interval suggest a possible 61 day modulation. Eighteen sets of PCA observations were obtained over an approx. one month interval in 1999. The flux variability measured with the PCA appears consistent with the possible period found with the ASM. The PCA measurements of the pulse period showed it to decrease non-monotonically and then to increase significantly. Doppler shifts due to orbital motion rather than accretion torques appear to be better able to explain the pulse period changes. Observations with the WFC during the extended outburst give an error box which is consistent with a previously determined PCA error box but is significantly smaller. The transient nature of XTE J1859+083 and the length of its pulse period are consistent with it being a Be/neutral star binary. The possible 61 day orbital period would be of the expected length for a Be star system with a 9.8 s pulse period.

Corbet, R. H. D.; intZand, J. J. M.; Levine, A. M.; Marshall, F. E.

2008-01-01

109

RXTE, VLBA, Optical, and Radio Monitoring of the Quasars 3C 279, PKS 1510--089, and 3C 273  

NASA Technical Reports Server (NTRS)

We are continuing our combined RXTE X-ray, VLBA imaging (at 43 GHz), optical (several observatories), and radio (University of Michigan Radio Astronomy Observatory) monitoring of the quasars 3C 279 and PKS 1510-089, and have started similar monitoring of 3C 273. X-ray flares in 3C 279 and PKS 1510-089 are associated with ejections of superluminal components. In addition, there is a close connection between the optical and X-ray variability of 3C 279. There is a strong correlation between the 14.5 GHz and X-ray variability of PKS 1510-089 in 1997 and 1998 (with the radio leading the X-ray) that becomes weaker in subsequent years. X-ray fluctuations occur on a variety of timescales in 3C 273, with a major prolonged outburst in mid-2001. The lead author will discuss the correlations in terms of inverse Compton models for the X-ray emission coupled with synchrotron models for the lower-frequency radiation. Synchrotron self-Compton models can explain the "reverse" time lag in PKS 1510-089 is well as the variable correlation between the X-ray variations and those at lower frequencies in this object and in 3C 279.

Marscher, A. P.; Jorstad, S. G.; Aller, M. F.; McHardy, I. M.; Balonek, T. J.

2001-01-01

110

ALGEBRA SEMINAR TALK Department of Computer Science  

E-print Network

ALGEBRA SEMINAR TALK WITH LILA KARI Department of Computer Science The University of Western for Theoretical Computer Science" Abstract: We are now witnessing exciting interactions between computer science absorbing notions, techniques and methodologies intrinsic to computer science and mathematics, theoretical

Sinnamon, Gordon J.

111

Montana State University 1 Computer Science  

E-print Network

Montana State University 1 Computer Science A computer science degree is highly curriculum is designed with considerable flexibility, due to the numerous types of computer science jobs. Students may then select from exciting computer science electives such as artificial intelligence

Maxwell, Bruce D.

112

Estudo espectral em raios-X duros de fontes do tipo Z com o HEXTE/RXTE  

NASA Astrophysics Data System (ADS)

Apresentam-se os resultados de um estudo espectral em raios-X de fontes do tipo Z. As fontes do tipo Z são binárias de raios-X de baixa massa (BXBM) com campo magnético intermediário (B~109G). Esta classe de fontes é composta por apenas 6 fontes Galácticas (a saber: ScoX-1, 9, 7, CygX-2, 5 e 0). A nossa análise se concentra na faixa de raios-X duros (E ~ 20keV), até cerca de 200keV, faixa ótima de operação do telescópio "High Energy X-ray Timing Experiment" (HEXTE), um dos três telescópios de raios-X à bordo do Rossi X-ray Timing Explorer (RXTE). Nossa motivação para tal estudo, uma busca de caudas em raios-X duros em fontes do tipo Z, foi o pouco conhecimento sobre a emissão nesta faixa de energia das referidas fontes quando comparadas, por exemplo, as fontes do tipo atoll (também BXBM). Apresentam-se a análise/redução de dados e explicita-se a maneira como o HEXTE mede o ru1do de fundo. Especial atenção é direcionada a este item devido a localização das fontes do tipo Z e também ao problema de contaminação por fontes próximas. Com exceção de ScoX-1, nenhuma cauda em raios-X duros foi encontrada para as outras fontes, a despeito de resultados de detecção dessas caudas em algumas fontes pelo satélite BeppoSAX. As interpretações deste resultado serão apresentadas. Do ponto de vista deste estudo, nós deduzimos que a produção de caudas de raios-X duros em fontes do tipo Z é um processo disparado quando, pelo menos, uma condição é satisfeita: o brilho da componente térmica do espectro precisa estar acima de um certo valor limiar de ~4´1036ergs-1.

D'Amico, F.; Heindl, W. A.; Rothschild, R. E.

2003-08-01

113

The Chandra and RXTE study of the galactic microquasar SS 433 and the surrounding nebula W50  

NASA Astrophysics Data System (ADS)

The X-ray binary system SS 433/W50 has baffled astrophysicists since its discovery in 1979. W50 has been classified as a Galactic supernova, remnant that harbors SS 433, an X-ray binary consisting of a compact object accreting matter from a companion star at a super-Eddington rate. The nature of the compact object is still under debate, but it is expelling relativistic jets that interact with W50, causing it to elongate along the jets axis and forming two X-ray lobes. This system has been studied in depth using Chandra (Moldowan et al., 2005), ROSAT and ASCA (SafiHarb & Ogelman 1997), RXTE (Safi-Harb & Petre 1999, Safi-Harb & Kotani 2002, 2003), and at millimeter wavelengths (Durouchoux et al. 2000). A 75 ksec Chandra observation of the western lobe of W50 is presented in this thesis. This region is of particular interest because it is rich with knots resulting from the interaction of a relativistic jet with a dense medium. The Chandra data provide the highest resolution X-ray image obtained to date. The spectroscopic results of this observation are presented and are targeted to (1) determine the nature of the X-ray emission and (2) correlate the X-ray emission with previous observations in the infrared and radio domains. It has been confirmed that at the site of interaction between the western jet and the interstellar gas the emission is non-thermal in nature. The helical pattern seen in radio is also observed with Chandra . No correlation was found between the X-ray and infrared emission. (Abstract shortened by UMI.)

Moldowan, Alyssa M.

114

Discovery and Monitoring of a new Black Hole Candidate XTE J1752-223 with RXTE: RMS spectrum evolution, BH mass and the source distance  

NASA Astrophysics Data System (ADS)

I will report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/high-soft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Compromising medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observation during the hard-to-soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

Shaposhnikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

2010-12-01

115

Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: Rms Spectrum Evolution, Black Hole Mass, and the Source Distance  

NASA Astrophysics Data System (ADS)

We report on the discovery and monitoring observations of a new galactic black hole (BH) candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on 2009 October 21 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/high-soft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass BH binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a blackbody spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (rms) variability in the RXTE/PCA energy band with the source spectral state and conclude that broadband variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition, and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hard-to-soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source of about 3.5 kpc.

Shaposhnikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

2010-11-01

116

Department of Computer Science College of Computing Sciences  

E-print Network

with computer science. This combination of skills is needed both in the pharmaceutical and biotechnologyDepartment of Computer Science College of Computing Sciences The Bachelor of Science and exciting field that stands at the intersection of biology, computer science and information technology

Bieber, Michael

117

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

118

Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State  

NASA Technical Reports Server (NTRS)

Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states". Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary s focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is > 40 GM/c(sup 2).

Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Joern; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, Jhn E.; Tramper, Frank

2009-01-01

119

Excitations of the torelon  

Microsoft Academic Search

The excitations of gluonic flux tube in a periodic lattice are examined. Monte Carlo simulations from an anisotropic lattice are presented and the comparison with effective string models is discussed.

K. J. Juge; J. Kuti; F. Maresca; C. Morningstar; M. Peardon

2004-01-01

120

Experiments on excitation waves  

Microsoft Academic Search

Recent trends in the experimentation on chemical and biochemical excitation waves are presented. In the Belousov-Zhabotinsky\\u000a reaction, which is the most suitable chemical laboratory system for the study of wave propagation in excitable medium, the\\u000a efficient control of wave dynamics by electrical fields and by light illumination is illustrated. In particular, the effects\\u000a of a feedback control are shown. Further

S. C. MOiler

121

Excitation Methods for Bridge Structures  

SciTech Connect

This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

1999-02-08

122

Highly excited atoms  

NASA Astrophysics Data System (ADS)

The physics of atoms in which an electron is excited to an exceptionally high energy level, termed Rydberg atoms, is discussed. Similarities between the essential properties of Rydberg atoms and the Bohr conception of the hydrogen atom are pointed out, and classical and quantum mechanical descriptions of atoms in a low-lying state and in a highly excited state are compared. Early observations of Rydberg atoms in the laboratory and in interstellar space are considered, and laboratory methods for the creation of Rydberg atoms are examined, with particular attention given to the excitation of alkali metal atoms to a particular Rydberg state by a tunable laser. Laser spectroscopic studies of the Stark effect in Rydberg atoms, Rydberg atom lifetimes with respect to electron tunneling and the effects of strong magnetic fields on the energy level structures of Rydberg atoms, which have revealed an unidentified apparent underlying symmetry in energy level structures, are presented.

Kleppner, D.; Littman, M. G.; Zimmerman, M. L.

1981-05-01

123

Multi-photon excitation microscopy  

PubMed Central

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

2006-01-01

124

Hydrogen bonding in the electronic excited state.  

PubMed

Because of its fundamental importance in many branches of science, hydrogen bonding is a subject of intense contemporary research interest. The physical and chemical properties of hydrogen bonds in the ground state have been widely studied both experimentally and theoretically by chemists, physicists, and biologists. However, hydrogen bonding in the electronic excited state, which plays an important role in many photophysical processes and photochemical reactions, has scarcely been investigated. Upon electronic excitation of hydrogen-bonded systems by light, the hydrogen donor and acceptor molecules must reorganize in the electronic excited state because of the significant charge distribution difference between the different electronic states. The electronic excited-state hydrogen-bonding dynamics, which are predominantly determined by the vibrational motions of the hydrogen donor and acceptor groups, generally occur on ultrafast time scales of hundreds of femtoseconds. As a result, state-of-the-art femtosecond time-resolved vibrational spectroscopy is used to directly monitor the ultrafast dynamical behavior of hydrogen bonds in the electronic excited state. It is important to note that the excited-state hydrogen-bonding dynamics are coupled to the electronic excitation. Fortunately, the combination of femtosecond time-resolved spectroscopy and accurate quantum chemistry calculations of excited states resolves this issue in laser experiments. Through a comparison of the hydrogen-bonded complex to the separated hydrogen donor or acceptor in ground and electronic excited states, the excited-state hydrogen-bonding structure and dynamics have been obtained. Moreover, we have also demonstrated the importance of hydrogen bonding in many photophysical processes and photochemical reactions. In this Account, we review our recent advances in electronic excited-state hydrogen-bonding dynamics and the significant role of electronic excited-state hydrogen bonding on internal conversion (IC), electronic spectral shifts (ESS), photoinduced electron transfer (PET), fluorescence quenching (FQ), intramolecular charge transfer (ICT), and metal-to-ligand charge transfer (MLCT). The combination of various spectroscopic experiments with theoretical calculations has led to tremendous progress in excited-state hydrogen-bonding research. We first demonstrated that the intermolecular hydrogen bond in the electronic excited state is greatly strengthened for coumarin chromophores and weakened for thiocarbonyl chromophores. We have also clarified that the intermolecular hydrogen-bond strengthening and weakening correspond to red-shifts and blue-shifts, respectively, in the electronic spectra. Moreover, radiationless deactivations (via IC, PET, ICT, MLCT, and so on) can be dramatically influenced through the regulation of electronic states by hydrogen-bonding interactions. Consequently, the fluorescence of chromophores in hydrogen-bonded surroundings is quenched or enhanced by hydrogen bonds. Our research expands our understanding of the nature of hydrogen bonding by delineating the interaction between hydrogen bonds and photons, thereby providing a basis for excited-state hydrogen bonding studies in photophysics, photochemistry, and photobiology. PMID:22070387

Zhao, Guang-Jiu; Han, Ke-Li

2012-03-20

125

Exploring Excited Hadrons  

E-print Network

Progress in extracting the spectrum of excited hadron resonances is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations are done with lighter pion masses is discussed, and the need for all-to-all quark propagators is emphasized.

Colin Morningstar

2008-10-24

126

Exploring Excited Hadrons  

E-print Network

Progress in extracting the spectrum of excited hadron resonances is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations are done with lighter pion masses is discussed, and the need for all-to-all quark propagators is emphasized.

Morningstar, C

2008-01-01

127

Positron excitation of neon  

NASA Technical Reports Server (NTRS)

The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

1990-01-01

128

Wave excited cable mooring dynamics by modal analysis  

E-print Network

klAVE EXCITED CABLE MOORING DYNAMICS BY MODAL ANALYSIS A Thesis RICHARD EARL DAVIS Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1977 Major... Subject: Civil Engineering WAVE EXCITED CABLE MOORING DYNAMICS BY MODAL ANALYSIS A Thesis by RICHARD EARL DAVIS Approved as to style and content by: (:( '. t(( (Co ? Chairman of Committee) 0~s (Co-Chairnin+of Committee) (Head of' Departme t...

Davis, Richard Earl

2012-06-07

129

The Astrophysics Science Division Annual Report 2008  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. This report includes the Division's activities during 2008.

Oegerle, William; Reddy, Francis; Tyler, Pat

2009-01-01

130

Static excitation test results of the partial rotor model for 70 MW class superconducting generator with quick response excitation  

SciTech Connect

The development of superconducting generators has been progressing in Japan since 1988 as a part of the New Sunshine Project of the Agency of Industrial Science Technology. Toshiba has been in charge of research and development of the quick response excitation type superconducting generator in the project. The authors are manufacturing the partial rotor model, which has the same rotor diameter and shorter winding length comparing with the 70 MW class quick response model machine. They assembled completely the inner rotor and carried out its excitation test in a cryostat. In this paper, they report the test result of heater quench, quench current, training, and pulse excitation.

Nakamura, H.; Matsumoto, H.; Hasegawa, H.; Nakanishi, K.; Inoue, K.; Sakai, M. [Toshiba Corp., Yokohama (Japan)] [Toshiba Corp., Yokohama (Japan); Ohshima, S. [Engineering Research Association for Superconductive Generation Equipment and Materials, Osaka (Japan)] [Engineering Research Association for Superconductive Generation Equipment and Materials, Osaka (Japan)

1996-07-01

131

Excitation of microseisms  

NASA Astrophysics Data System (ADS)

Excitation of microseisms is generally considered to be due to pressure change at ocean bottom, for which Longuet-Higgins derived his celebrated formula in 1950. Use of this formula is an approximation, however. Comparison with a more rigorous normal-mode formula shows that this conventional approach is acceptable for ocean depths less than 1 km but fails in deep oceans. On the other hand, there seems to be a multitude of evidence that source region for double-frequency microseim is near the coast and thus is generally in shallow water. An evidence from buoy data for nonlinearity in ocean waves is presented to support this view. If a source region is in shallow water, use of the Longuet-Higgins pressure formula at ocean bottom for the excitation of microseisms is justified, although one should pay attention to ocean depths very carefully.

Tanimoto, Toshiro

2007-03-01

132

Magnetostrictive resonance excitation  

DOEpatents

The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

1992-01-01

133

Apparatus for photon excited catalysis  

NASA Technical Reports Server (NTRS)

An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

Saffren, M. M. (inventor)

1977-01-01

134

Parametric Excitation of a DWSC  

E-print Network

to parametric excitation. This thesis examines the phenomenon of parametric excitation with respect to roll motion in head seas, using time-domain simulation and stability analysis. It examines the DWSC's susceptibility to parametric instability using the same...

Lakhotia, Chandan

2011-08-08

135

Aperture excited dielectric antennas  

NASA Technical Reports Server (NTRS)

The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.

Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.

1974-01-01

136

Capturing Excitement: Oceanography  

ERIC Educational Resources Information Center

Describes four elementary school earth science activities. Each student experience is designed to help children answer questions about the ocean floor, continental drift, volcanism and mountain chains. Includes a bibliography of related articles, books, and maps. (JM)

Boyer, Robert E.; Butts, David P.

1971-01-01

137

Life Science  

NSDL National Science Digital Library

For decades, many of the nation's life science classrooms have been anything but lively. Biology has been criticized for being content heavy, overloaded with vocabulary, and tested by rote. Six to seven hundred pages of text, presented to teenagers with limited abilities to reason, constituted what in most cases was the only required science in high schools. By contrast, the classroom of a life science teacher who is moving toward the Standards provides an exciting environment for inquiry and a core of content that is smaller but in greater depth than in the past. Topics are covered in more detail, coursework is integrated, and both teachers and students feel challenged. This free selection includes an inquiry-based, life science lesson and the Table of Contents.

2004-01-01

138

Excitation and Characterization of Chladni Plate Patterns  

NASA Astrophysics Data System (ADS)

When a thin metal plate with a small amount of sand on it is made to vibrate, aesthetically pleasing sand patterns can form along the nodal lines of the plate. These symmetric patterns are called Chladni Patterns. Students taking PHY 101 Physical Science in the Arts at Eastern Michigan University create these patterns by pulling a violin bow across the edge of a plate, or by using a mechanical oscillator to drive the center of a plate. These two methods only allow a small subset of all possible points on the plate to be excited. We designed and built an electronic device that allows its user to excite the plate at any point. We present patterns created with this electronic device and other methods, and describe ways to model the observed patterns.

Bourke, Shannon; Behringer, Ernest

2011-04-01

139

Excited-State Dynamics in Folic Acid and 6-CARBOXYPTERIN upon Uva Excitation  

NASA Astrophysics Data System (ADS)

The excited-state dynamics of folic acid (FA) and 6-carboxypterin (6CP) are poorly understood and work is needed to uncover the relaxation pathways that ultimately lead to their oxidative damage of DNA. In our approach, broad-band transient absorption spectroscopy was used to monitor the evolution of the excited states in FA and 6CP in basic aqueous solution upon excitation at 350 nm. In addition, quantum-chemical calculations were performed to assist in the interpretation of the experimental results and in the postulation of kinetic mechanisms. The combined experimental and computational results support a kinetic model where excitation of FA results in ultrafast charge separation (? = 0.6 ps), which decays back to the ground state primarily by charge recombination with a lifetime of 2.2 ps. A small fraction of the charge transfer state undergoes intersystem crossing to populate the lowest-energy triplet state with a lifetime of 200 ps. On the other hand, a large fraction of the initially excited singlet state in 6CP decays by fluorescence emission with a lifetime of 100 ps, while intersystem crossing to the triplet state occurs with a lifetime of 4.4 ns. The potential implications of these results to the oxidative damage of DNA by FA and 6CP will be discussed. Funding from the National Science Foundation is gratefully acknowledged (CHE-1255084).

Huang, Huijuan; Vogt, R. Aaron; Crespo-Hernandez, Carlos E.

2013-06-01

140

Imaginative Early Science  

ERIC Educational Resources Information Center

Scientific learning in the early years quite correctly focuses on the development of skills. However, at this stage of learning, science should also be about developing motivational attitudes to encourage children to explore the world around them and convince them that science is an exciting subject. Practical experiential play activities do this…

Johnston, Jane

2003-01-01

141

Undergraduate Faculty of Science  

E-print Network

Undergraduate Chemistry Faculty of Science #12;bristol.ac.uk/study Chemistry offers exciting develop new drugs to fight against disease, engage heavily in nanotechnology, biotechnology and forensic science. Chemistry is of course fundamental to solving the problems of climate change. The School

Bristol, University of

142

Science Career Magazine.  

ERIC Educational Resources Information Center

This magazine is designed for teachers and students in junior and senior high schools. It is intended to help students become more aware about what scientists and engineers do, what's new and exciting in the fields of science and engineering, and what satisfactions might be expected from a career in one of the many different areas of science and…

Halsey, Linda B., Ed.; Sweeley, Charles C., Ed.

143

Expanding Science Knowledge: Enabled by Nuclear Power  

NASA Technical Reports Server (NTRS)

The availability of Radioisotope Power Sources (RPSs) power opens up new and exciting mission concepts (1) New trajectories available (2) Power for long term science and operations Astonishing science value associated with these previously non-viable missions

Clark, Karla B.

2011-01-01

144

National Computational Science Education Consortium (NCSEC)  

NSDL National Science Digital Library

Serving as a national educational computational science clearinghouse, this website offers math and science teachers everywhere an array of online educational tools and exciting teaching modules that can be used in the classroom.

145

Computer science olympiad: exploring computer science through competition  

Microsoft Academic Search

Generating interest in specialized areas of Computer Science (CS) is one of the goals of the department of Computer and Information Science at Spelman College as with most departments. Achieving this goal in a new, exciting, and innovative manner provided the inspiration to establish the Spelman College Computer Science Olympiad (SCCSO). The SCCSO is patterned after the Olympics athletic event.

Iretta B. C. Kearse; Charles Hardnett

2008-01-01

146

Computer science olympiad: exploring computer science through competition  

Microsoft Academic Search

Generating interest in specialized areas of Computer Science (CS) is one of the goals of the department of Computer and Information Science at Spelman College as with most departments. Achieving this goal in a new, exciting, and innovative manner provided the inspiration to establish the Spelman College Computer Science Olympiad (SC CS Olympiad). The SC CS Olympiad is patterned after

Iretta B. Kearse; Charles R. Hardnett

2008-01-01

147

Plasmonic excitations in nanostructures  

NASA Astrophysics Data System (ADS)

The prevalent classical model of plasmonic calculations for nano-scale metallic clusters is based on the Mie solution. Which consists of solving Maxwell's equations with the material being represented by a dielectric function on its spatial location. However, such a semi-empirical continuum description necessarily breaks down beyond a certain level of coarseness introduced by atomic length scales. Even the bulk based model used for the dielectric function fails by itself. This limitation of the Mie solution has been established by a quantum mechanical calculation with self-consistent treatment of the dielectric response. In order to understand better the plasmonic excitations at nearly atomic scale, we explored the collective electromagnetic response of atomic chains of various sizes and geometries, and we also computed plasmons in graphene in the presence of an impurity. For the atomic chains, we calculated the plasmonic resonances as a function of the system shape, direction of the external applied field, electron filling and atomic separation. Their frequency, oscillator strength and spatial modulation of the induced charge density were analyzed. It was shown that longitudinal and transverse modes can be controlled in amplitude and frequency by the cluster size. It was also observed an abrupt dependence of the modes on the electronic filling. We also find that changes in atomic spacings have a very different impact on low-energy vs. high-energy modes. And it was seen that changing the position of a single atom in a nanostructure can completely alter its collective dielectric response. This strong sensitivity to small changes is the key to controlling the dielectric properties of atomic scale structures, and it can thus become the gateway to a new generation of quantum devices which effectively utilize quantum physics for new functionalities. For graphene it was shown that impurities induce the formation of nanoscale localized plasmonic excitations in graphene sheets. It was studied the dependence of these excitations on the magnitude and size of the impurity potential and electronic filling. It was shown that the impurity potential and doping can be used to tune the properties of nano-plasmonic excitations, demonstrating that graphene is an inherently plasmonic material. It was found that the chemical potential can be used to turn them on and off, but it does not affect their frequency. While their frequency and amplitude can be tuned by varying the strength of the impurity potential. The method employed for this calculation had not been seen before. In principle the results discussed can be tested experimentally by high-frequency optical probes or STM. These results showed that collective excitations in finite systems have properties different from their bulk correspondents. Since there is not a macroscopic number of electrons in the system, the variation of one single electron causes observable differences. The localized resonant modes are very sensitive to even small variations in the system, for example the position of a single atom. This makes it difficult to establish general rules about the properties of collective excitations in atomic structures. On the other hand it also provides a vast range of possibilities that can be explored for achieving new functionalities.

Muniz, Rodrigo Angelo

148

Self-excitation of single nanomechanical pillars  

NASA Astrophysics Data System (ADS)

Self-excitation is a mechanism that is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators (Nedic and Lipo 2000 IEEE/IAS Conf. Records (Rome, Italy) vol 1 pp 51-6), a good and widely visible example of which is the wind turbine farm (Muljadi et al 2005 J. Sol. Energy Eng. 127 581-7). In other words, a static force, such as the wind acting on rotor blades, can generate a resonant excitation at a certain mechanical frequency. For nanomechanical systems (Craighead 2000 Science 290 1532-5 Roukes 2001 Phys. World 14 25-31 Cleland 2003 Foundations of Nanomechanics (Berlin: Springer); Ayari et al 2007 Nano Lett. 7 2252-7 Koenig et al 2008 Nat. Nanotechnol. 3 482-4) such a self-excitation (SE) mechanism is also highly desirable, because it can generate mechanical oscillations at radio frequencies by simply applying a dc bias voltage. This is of great importance for low-power signal communication devices and detectors, as well as for mechanical computing elements. For a particular nanomechanical system—the single electron shuttle—this effect was predicted some time ago by Gorelik et al (Phys. Rev. Lett. 80 4526-9). Here, we use a nanoelectromechanical single electron transistor (NEMSET) to demonstrate self-excitation for both the soft and hard regimes, respectively. The ability to use self-excitation in nanomechanical systems may enable the detection of quantum mechanical backaction effects (Naik et al 2006 Nature 443 193-6) in direct tunneling, macroscopic quantum tunneling (Savelev et al 2006 New J. Phys. 8 105-15) and rectification (Pistolesi and Fazio 2005 Phys. Rev. Lett. 94 036806-4). All these effects have so far been overshadowed by the large driving voltages that had to be applied.

Kim, Hyun S.; Qin, Hua; Blick, Robert H.

2010-03-01

149

Highly excited atoms  

SciTech Connect

Highly excited atoms are often called Rydberg atoms. These atoms have a wealth of exotic properties which are discussed. Of special interest, are the effects of electric and magnetic fields on Rydberg atoms. Ordinary atoms are scarcely affected by an applied electric or magnetic field; Rydberg atoms can be strongly distorted and even pulled apart by a relatively weak electric field, and they can be squeezed into unexpected shapes by a magnetic field. Studies of the structure of Rydberg atoms in electric and magnetic fields have revealed dramatic atomic phenomena that had not been observed before. (SC)

Kleppner, D.; Littman, M.G.; Zimmerman, M.L.

1981-05-01

150

Quasi-Periodic Oscillations in Short Recurring Bursts of the magnetars SGR 1806-20 and SGR 1900+14 Observed With RXTE  

E-print Network

Quasi-periodic oscillations (QPOs) observed in the giant flares of magnetars are of particular interest due to their potential to open up a window into the neutron star interior via neutron star asteroseismology. However, only three giant flares have been observed. We therefore make use of the much larger data set of shorter, less energetic recurrent bursts. Here, we report on a search for QPOs in a large data set of bursts from the two most burst-active magnetars, SGR 1806-20 and SGR 1900+14, observed with the Rossi X-ray Timing Explorer (RXTE). We find a single detection in an averaged periodogram comprising 30 bursts from SGR 1806-20, with a frequency of 57 Hz and a width of 5 Hz, remarkably similar to a giant flare QPO observed from SGR 1900+14. This QPO fits naturally within the framework of global magneto-elastic torsional oscillations employed to explain the giant flare QPOs. Additionally, we uncover a limit on the applicability of Fourier analysis for light curves with low background count rates and s...

Huppenkothen, D; Watts, A L; Gö?ü?, E

2014-01-01

151

The accretion flow to the intermittent accreting ms pulsar, HETE J1900.1-2455, as observed by XMM-Newton and RXTE  

E-print Network

We present a study of the accretion flow to the intermittent accreting millisecond pulsar, HETE J1900.1-2455, based on observations performed simultaneously by XMM-Newton and RXTE. The 0.33-50 keV spectrum is described by the sum of a hard Comptonized component originated in an optically thin {\\tau}~1 corona, a soft kTin~0.2 keV component interpreted as accretion disc emission, and of disc reflection of the hard component. Two emission features are detected at energies of 0.98(1) and 6.58(7) keV, respectively. The latter is identified as K{\\alpha} transition of Fe XXIII-XXV. A simultaneous detection in EPIC-pn, EPIC-MOS2, and RGS spectra favours an astrophysical origin also for the former, which has an energy compatible with Fe-L{\\alpha} and helium-like Ne-K{\\alpha} transitions. Broadness of the two features suggests a common origin, resulting from reflection in an accretion disc with inclination of (30+4{\\deg}), and extending down to Rin=25(+16,-11) gravitational radii from the compact object. However, the s...

Papitto, A; Di Salvo, T; Egron, E; Bozzo, E; Burderi, L; Iaria, R; Riggio, A; Menna, M T

2012-01-01

152

Analysis and Interpretation of Hard X-ray Emission fromthe Bullet Cluster (1E0657-56), the Most Distant Cluster of Galaxies Observed by the RXTE  

SciTech Connect

Evidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons. New windows in the Extreme Ultraviolet and Hard X-ray ranges have provided for more powerful tools for the investigation of this phenomenon. Detection of hard X-rays in the 20 to 100 keV range have been reported from several clusters of galaxies, notably from Coma and others. Based on these earlier observations we identified the relatively high redshift cluster 1E0657-56 (also known as RX J0658-5557) as a good candidate for hard X-ray observations. This cluster, also known as the bullet cluster, has many other interesting and unusual features, most notably that it is undergoing a merger, clearly visible in the X-ray images. Here we present results from a successful RXTE observations of this cluster. We summarize past observations and their theoretical interpretation which guided us in the selection process. We describe the new observations and present the constraints we can set on the flux and spectrum of the hard X-rays. Finally we discuss the constraints one can set on the characteristics of accelerated electrons which produce the hard X-rays and the radio radiation.

Petrosian, Vahe; /Stanford U., Phys. Dept. /SLAC /Stanford U., Appl. Phys. Dept.; Madejski, Greg; /SLAC; Luli, Kevin; /Stanford U., Phys. Dept.

2006-08-16

153

SIMULTANEOUS OBSERVATIONS OF PKS 2155-304 WITH HESS, FERMI, RXTE, AND ATOM: SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE  

SciTech Connect

We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

Aharonian, F.; Bernloehr, K.; Bochow, A.; Buehler, R. [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany); Akhperjanian, A. G. [Yerevan Physics Institute, 2 Alikhanian Brothers Street, 375036 Yerevan (Armenia); Anton, G.; Brucker, J. [Universitaet Erlangen-Nuernberg, Physikalisches Institut, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany); Barres de Almeida, U.; Chadwick, P. M. [University of Durham, Department of Physics, South Road, Durham DH1 3LE (United Kingdom); Bazer-Bachi, A. R.; Borrel, V. [Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, BP 44346, F-31028 Toulouse Cedex 4 (France); Becherini, Y. [Astroparticule et Cosmologie (APC), CNRS, Universite Paris 7 Denis Diderot, 10, rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); Behera, B. [Landessternwarte, Universitaet Heidelberg, Koenigstuhl, D-69117 Heidelberg (Germany); Boisson, C. [LUTH, Observatoire de Paris, CNRS, Universite Paris Diderot, 5 Place Jules Janssen, 92190 Meudon (France); Brion, E.; Brun, P. [IRFU/DSM/CEA, CE Saclay, F-91191 Gif-sur-Yvette, Cedex (France); Bulik, T. [Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw (Poland); Buesching, I. [Unit for Space Physics, Northwest University, Potchefstroom 2520 (South Africa); Boutelier, T. [Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Universite Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9 (France); Charbonnier, A. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Denis Diderot Paris 7, CNRS/IN2P3, 4 Place Jussieu, F-75252, Paris Cedex 5 (France)], E-mail: lucie.gerard@apc.univ-paris7.fr, E-mail: berrie@in2p3.fr, E-mail: sanchez@poly.in2p3.fr, E-mail: jchiang@slac.stanford.edu (and others)

2009-05-10

154

Analysis and Interpretation of Hard X-ray Emission from the Bullet Cluster (1E0657-56), the Most Distant Cluster of Galaxies Observed by RXTE  

E-print Network

Evidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons. New windows in the Extreme Ultraviolet and Hard X-ray ranges have provided for more powerful tools for the investigation of this phenomenon. Detection of hard X-rays in the 20 to 100 keV range have been reported from several clusters of galaxies, notably from Coma and others. Based on these earlier observations we identified the relatively high redshift cluster 1E0657-56 (also known as RX J0658-5557) as a good candidate for hard X-ray observations. This cluster, also known as the bullet cluster, has many other interesting and unusual features, most notably that it is undergoing a merger, clearly visible in the X-ray images. Here we present results from a successful RXTE observations of this cluster. We summarize past observations and their theoretical interpretation which guided us in the selection process. We describe the new observations and present the constraints we can set on the flux and spectrum of the hard X-rays. Finally we discuss the constraints one can set on the characteristics of accelerated electrons which produce the hard X-rays and the radio radiation.

Vahe' Petrosian; Greg Madejski; Kevin Luli

2006-08-22

155

Neutron Scattering Studies of spin excitations in hole-doped  

E-print Network

Neutron Scattering Studies of spin excitations in hole-doped Ba0.67K0.33Fe2As2 superconductor Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA, 4 University, West Lafayette, Indiana 47907, USA. We report inelastic neutron scattering experiments on single

Wang, Wei Hua

156

Why are Games Exciting and Stimulating? Aviezri S. Fraenkel  

E-print Network

Why are Games Exciting and Stimulating? Aviezri S. Fraenkel Computer Science and Applied of games. It serves a dual purpose: (i) an introduc- tion for the uninitiated, and (ii) a way to introduce youth and others to mathematics in a pleasing and delightful way. 1 The lure of games Games have

Fraenkel, Aviezri

157

Fusion excitation function revisited  

E-print Network

We report on a comprehensive systematics of fusion-evaporation and/or fusion-fission cross sections for a very large variety of systems over an energy range 4-155 A.MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry.For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A.MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A.MeV.

Ph. Eudes; Z. Basrak; F. Sébille; V. de la Mota; G. Royer; M. Zori?

2012-09-07

158

Follow-Up with Students after 6 Years of Participation in Project Excite  

ERIC Educational Resources Information Center

Project EXCITE is a program for minority students that supplements the regular school offerings with an emphasis on enhancing students' interest and performance in math and science. This study examines the experience and perceptions of 14 student participants in the program and their parents. In student and parent interviews, Project EXCITE was…

Lee, Seon-Young; Olszewski-Kubilius, Paula; Peternel, George

2009-01-01

159

Optically excited states in positronium  

NASA Technical Reports Server (NTRS)

Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.

Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.

1990-01-01

160

The Balloons Go Up for Science.  

ERIC Educational Resources Information Center

Describes the planning and implementation of a science week intended to raise the awareness of science in an elementary school. Educational requirements included exciting science happenings and concentrated science teaching of a high standard. The week included demonstrations, guest speakers, and schoolwide assemblies. Demonstrations included the…

Fayle, Maureen

1998-01-01

161

Attosecond Photoscopy of Plasmonic Excitations  

NASA Astrophysics Data System (ADS)

We propose an experimental arrangement to image, with attosecond resolution, transient surface plasmonic excitations. The required modifications to state-of-the-art setups used for attosecond streaking experiments from solid surfaces only involve available technology. Buildup and lifetimes of surface plasmon polaritons can be extracted and local modulations of the exciting optical pulse can be diagnosed in situ.

Lupetti, Mattia; Hengster, Julia; Uphues, Thorsten; Scrinzi, Armin

2014-09-01

162

Coulomb excitation of 31Mg  

NASA Astrophysics Data System (ADS)

The ground state properties of 31Mg indicate a change of nuclear shape at N=19 with a deformed J=1/2 intruder state as a ground state, implying that 31Mg is part of the “island of inversion”. The collective properties of excited states were the subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam. De-excitation ?-rays were detected by the MINIBALL ?-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of 31Mg was extended. Spin and parity assignment of the 945 keV state yielded 5/2 and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that for the N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration.

Seidlitz, M.; Mücher, D.; Reiter, P.; Bildstein, V.; Blazhev, A.; Bree, N.; Bruyneel, B.; Cederkäll, J.; Clement, E.; Davinson, T.; Van Duppen, P.; Ekström, A.; Finke, F.; Fraile, L. M.; Geibel, K.; Gernhäuser, R.; Hess, H.; Holler, A.; Huyse, M.; Ivanov, O.; Jolie, J.; Kalkühler, M.; Kotthaus, T.; Krücken, R.; Lutter, R.; Piselli, E.; Scheit, H.; Stefanescu, I.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.

2011-06-01

163

Excited waves in shear layers  

NASA Technical Reports Server (NTRS)

The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

Bechert, D. W.

1982-01-01

164

Earth Sciences Earth Sciences  

E-print Network

Earth Sciences Earth Sciences Undergraduate Studies #12;Department of Earth Sciences2 Royal;3Department of Earth Sciences Earth Sciences The Department of Earth Sciences at Royal Holloway.ac.uk/studyhere Contents Why study Earth Sciences? 4 Earth Sciences at Royal Holloway 5 Admissions and entry requirements 6

Royal Holloway, University of London

165

Exploring the Place of Exemplary Science Teaching. This Year in School Science 1993.  

ERIC Educational Resources Information Center

Exemplary science teaching is an experience that fosters wonder, excitement, and risk-taking. This book presents essays which attempt to describe the culture of classrooms of exemplary science teachers. Chapter titles are: "Exploring the Place of Exemplary Science Teaching" (Ann E. Haley-Oliphant); "The Voices of Exemplary Science Teachers" (Ann…

Haley-Oliphant, Ann E., Ed.

166

Effects of dark atom excitations  

E-print Network

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

Cudell, Jean-René; Wallemacq, Quentin

2014-01-01

167

Coulomb excitation of 107In  

NASA Astrophysics Data System (ADS)

The radioactive isotope 107In was studied using sub-barrier Coulomb excitation at the REX-ISOLDE facility at CERN. Two ? rays were observed during the experiment, corresponding to the low-lying 11/2+ and 3/2- states. The reduced transition probability of the 11/2+ state was determined with the semiclassical Coulomb excitation code gosia2. The result is discussed in comparison to large-scale shell-model calculations, previous unified-model calculations, and earlier Coulomb excitation measurements in the odd-mass In isotopes.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Heyde, K.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2013-01-01

168

Industrial applications of photonuclear resonance excitation  

E-print Network

Photonuclear resonance excitation refers to a variety of photonuclear interaction processes that lead to the excitation of a nucleus from some initial state to a higher energy nuclear state. Typical excited nuclear state ...

Chichester, David Lee, 1971-

2000-01-01

169

Electron impact excitation of rubidium  

NASA Astrophysics Data System (ADS)

The electron energy-loss spectrum of rubidium at 40 eV and scattering angle 8° has been recorded. The noticeable features are analysed. Differential cross sections for the resonance excitation are determined.

Predojevi?, B.; Pej?ev, V.; Ševi?, D.; Leki?, S.; Srivastava, R.; Stauffer, A.; Marinkovi?, B. P.

2012-11-01

170

Multiphonon excitations in 62Zn  

NASA Astrophysics Data System (ADS)

We studied excited states in 62Zn up to an excitation energy of 5.5 MeV via the 61Ni( 3He, 2n ?) reaction at the Cologne Tandem accelerator with the high-efficiency HORUS cube spectrometer. We identified several multi-phonon excitations, especially two fragments of the one-phonon mixed-symmetry state 21,MS+ based on effective M1 and E2 transition strengths. The quantities were obtained from ?? angular correlation and Doppler-shift measurements. Shell-model calculations performed for 62Zn give clear support for the fragmentation of the one-phonon mixed-symmetry 21,MS+ state. The assumption of 62Zn being a vibrator-like nucleus is supported by calculations of excitation energies and E2 and M1 transition strengths within the U(5) limit of the neutron-proton Interacting Boson Model.

Albers, M.; Mücher, D.; Bernards, C.; Blazhev, A.; Fransen, C.; Heinze, S.; Jolie, J.; Lisetskiy, A.; Petkov, P.; Radeck, D.; Zell, K. O.

2010-12-01

171

Versatile single-molecule multi-color excitation and detection fluorescence setup for studying biomolecular dynamics  

E-print Network

(2004) Improvement of detected intensity in confocal microscopy by using reflecting optical system Rev OF SCIENTIFIC INSTRUMENTS 82, 113702 (2011) Versatile single-molecule multi-color excitation and detection of Chemical and Life Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal

Walter, Nils G.

172

Electron-excited molecule interactions  

SciTech Connect

In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10{sup 6} to 10{sup 7} times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs.

Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

1991-01-01

173

Redox Control of Cardiac Excitability  

PubMed Central

Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

Aggarwal, Nitin T.

2013-01-01

174

A Comparison of the Variability of the Symbiotic X-ray Binaries GX 1+4, 4U 1954+31, and 4U 1700+24 from Swift/BAT and RXTE/ASM Observations  

NASA Technical Reports Server (NTRS)

We present an analysis of the X-ray variability of three symbiotic X-ray binaries, GX 1+4, 4U 1700+24, and 4U 1954+31, using observations made with the Swift Burst Alert Telescope (BAT) and the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Observations of 4U 1954+31 with the Swift BAT show modulation at a period near 5 hours. Models to explain this modulation are discussed including the presence of an exceptionally slow X-ray pulsar in the system and accretion instabilities. We conclude that the most likely interpretation is that 4U 1954+31 contains one of the slowest known X-ray pulsars. Unlike 4U 1954+31, neither GX 1+4 nor 4U 1700+24 show any evidence for modulation on a timescale of hours. An analysis of the RXTE ASM light curves of GX l+4, 4U 1700+24, and 4U 1954+31 does not show the presence of periodic modulation in any source, although there is considerable variability on long timescales for all three sources. There is no modulation in GX 1+4 on either the optical 1161 day orbital period or a previously reported 304 day X-ray period. For 4U 1700+24 we do not confirm the 404 day period previously proposed for this source from a shorter duration ASM light curve.

Corbet, R. H. D.; Sokoloski, J. L.; Mukai, K.; Markwardt, C. B.; Tueller, J.

2007-01-01

175

Faculty of Science Medical Physics  

E-print Network

Faculty of Science Medical Physics If you like physics and mathematics, but want a career in the rapidly expanding health sciences, then this honours BSc is for you. www.uwindsor.ca/physics Medical Physics opens the way to exciting new possibilities for career opportunities in the applications

176

Investigating Science with Young Children.  

ERIC Educational Resources Information Center

Teaching science by a process approach is an exciting adventure for both teachers and their students. Process science is an open ended approach, and the direction learning will take place is determined, for the most part, by the children. This method requires that teachers understand how children learn, know the possibilities a topic offers for…

Althouse, Rosemary

177

Science Shorts: More Than One Way to Investigate  

NSDL National Science Digital Library

An exciting element of science fairs is that they give students the opportunity to explore various interests through scientific investigation. Many students, however, mistakenly think that all investigations are experiments. This lesson can help broaden students' conceptions of science.

2007-12-01

178

Sizing Up Science Competitions  

NSDL National Science Digital Library

Each fall, teachers receive many packets in the mail announcing exciting science contests for students. Because many of these contests promise prizes, trips, and awards for winning students and their teachers, it is tempting for teachers to try to enter e

Bettac, Teresa F.

1999-09-01

179

About Behavioral and Social Sciences Research  

E-print Network

1 About Behavioral and Social Sciences Research The 21st century is an exciting time and behavioral and social sciences research will lead to the most effective interventions. What is Behavioral and Social Sciences Research? "Behavioral" is a term that covers a lot of ground. It refers to what people do

Baker, Chris I.

180

Using Concept Maps in the Science Classroom  

ERIC Educational Resources Information Center

Teaching science in middle school is both rewarding and demanding. Creating an exciting learning environment with a rich science curriculum that engages all students is challenging enough. Monitoring the progress of as many as 150 individual students and knowing that they understand the science concepts we are teaching can be overwhelming. How can…

Vanides, Jim; Yin, Yue; Tomita, Miki; Ruiz-Primo, Maria Araceli

2005-01-01

181

Orthogonal fluxgate employing discontinuous excitation  

NASA Astrophysics Data System (ADS)

In this work, we suggest a new method for the reduction of the power consumption of an orthogonal fluxgate employing an amorphous wire. In order to reduce the power consumption, we introduce idle intervals in the fluxgate excitation. In fluxgates where the excitation current is applied directly to the wire core, the excitation wave form can easily be manipulated due to the very small impedance of the wire core. The resulted discontinuities in the excitation increase the fluxgate noise by a factor of about 3.5. In order to eliminate this excess noise, we simply discard the data related to the excitation idle intervals from the signal processing of the fluxgate output. As a result, we have reduced the fluxgate power consumption by a factor of 16, from 6.4 mW at 100% duty cycle down to 0.4 mW at 6.25% duty cycle. It is important to note that the reduction of power consumption is obtained without decreasing the fluxgate resolution.

Weiss, Eyal; Paperno, Eugene; Plotkin, Anton

2010-05-01

182

The Internet Encyclopedia of Science  

NSDL National Science Digital Library

Visitors can learn astonishing facts in historical astronomy, astrobiology, astrophysics, space missions, and many more space science topics at this comprehensive website. David Darling, a British astronomer and science writer, provides straightforward explanations of seemingly difficult concepts. In addition to an easily navigable alphabetical list and a keyword search, the encyclopedia is interlinked so that users can easily progress through the materials. The website also features the latest space science news stories as well as archives of exciting events.

2005-12-30

183

Modeling Excitable Systems: Reentrant Tachycardia  

E-print Network

Excitable membranes are an important type of nonlinear dynamical system and their study can be used to provide a connection between physical and biological circuits. We discuss two models of excitable membranes important in cardiac and neural tissues. One model is based on the Fitzhugh-Nagumo equations and the other is based on a three-transistor excitable circuit. We construct a circuit that simulates reentrant tachycardia and its treatment by surgical ablation. This project is appropriate for advanced undergraduates as a laboratory capstone project, or as a senior thesis or honors project, and can also be a collaborative project, with one student responsible for the computational predictions and another for the circuit construction and measurements.

Jarrett L. Lancaster; Esther M. Leise; Edward H. Hellen

2008-07-02

184

Excitation optimization for damage detection  

SciTech Connect

A technique is developed to answer the important question: 'Given limited system response measurements and ever-present physical limits on the level of excitation, what excitation should be provided to a system to make damage most detectable?' Specifically, a method is presented for optimizing excitations that maximize the sensitivity of output measurements to perturbations in damage-related parameters estimated with an extended Kalman filter. This optimization is carried out in a computationally efficient manner using adjoint-based optimization and causes the innovations term in the extended Kalman filter to be larger in the presence of estimation errors, which leads to a better estimate of the damage-related parameters in question. The technique is demonstrated numerically on a nonlinear 2 DOF system, where a significant improvement in the damage-related parameter estimation is observed.

Bement, Matthew T [Los Alamos National Laboratory; Bewley, Thomas R [UCSD

2009-01-01

185

Calculation of molecular excitation rates  

NASA Technical Reports Server (NTRS)

State-to-state collisional excitation rates for interstellar molecules observed by radio astronomers continue to be required to interpret observed line intensities in terms of local temperatures and densities. A problem of particular interest is collisional excitation of water which is important for modeling the observed interstellar masers. In earlier work supported by a different NASA Grant, excitation of water in collisions with He atoms was studied; after many years of successively more refined calculations that problem now seems to be well understood, and discrepancies with earlier experimental data for related (pressure broadening) phenomena are believed to reflect experimental errors. Because of interstellar abundances, excitation by H2, the dominant interstellar species, is much more important than excitation by He, although it has been argued that rates for excitation by these are similar. Under the current grant theoretical study of this problem has begun which is greatly complicated by the additional degrees of freedom which must be included both in determining the interaction potential and also in the molecular scattering calculation. We have now computed the interaction forces for nearly a thousand molecular geometries and are close to having an acceptable global fit to these points which is necessary for the molecular dynamics calculations. Also, extensive modifications have been made to the molecular scattering code, MOLSCAT. These included coding the rotational basis sets and coupling matrix elements required for collisions of an asymmetric top with a linear rotor. A new method for numerical solution of the coupled equations has been incorporated. Because of the long-ranged nature of the water-hydrogen interaction it is necessary to integrate the equations to rather large intermolecular separations, and the integration methods previously available in MOLSCAT are not ideal for such cases. However, the method used by Alexander in his HIBRIDON code is particularly suited for such cases. We have obtained this code and incorporated that part which solves the coupled differential equations as an option in the MOLSCAT program.

Flynn, George

1993-01-01

186

The exciting thing about recombinant DNA, Victor McElhenySite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

` Victor McElheny DNAi Location:Manipulation>Revolution>players>The controversy A new world of exploration Former science journalist Victor McElheny muses on the excitement that surrounded the new genetic technology.

2008-03-26

187

Electron impact excitation of coronene  

NASA Technical Reports Server (NTRS)

A preliminary study of the electron-impact excitation of thermally evaporated coronene at 550 C was carried out using electron-energy-loss spectroscopy. Measurements of the energy-loss spectra of coronene at high (100 eV) and low (5-20 eV) impact energies are presented. One of the high-energy spectra was converted to an apparent generalized oscillator strength spectrum and compared to the photoabsorption spectrum of coronene. Observations concerning vibrational excitation of coronene by electron impact are also presented and discussed.

Khakoo, M. A.; Ratliff, J. M.; Trajmar, S.

1990-01-01

188

Autoresonant Excitation of Antiproton Plasmas  

SciTech Connect

We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.

Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby British Columbia, V5A 1S6 (Canada); Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Carpenter, P. T.; Hurt, J. L.; Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849-5311 (United States); Cesar, C. L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil)

2011-01-14

189

Stochastic excitation of stellar oscillations  

E-print Network

Excitation of solar oscillations is attribued to turbulent motions in the solar convective zone. It is also currently believed that oscillations of low massive stars (M <2 Mo) - which possess an upper convective zone - are stochastically excited by turbulent convection in their outer layers. A recent theoretical work (Samadi & Goupil, 2001 ; Samadi et al, 2001) supplements and reinforces this theory. This allows the use of any available model of turbulence and emphasizes some recent unsolved problems which are brought up by these new theoretical developments.

Reza Samadi

2001-08-22

190

Magnification of photonic crystal fluorescence enhancement via TM resonance excitation and TE resonance extraction on a dielectric nanorod surface  

E-print Network

Magnification of photonic crystal fluorescence enhancement via TM resonance excitation and TE.1088/0957-4484/21/12/125203 Magnification of photonic crystal fluorescence enhancement via TM resonance excitation and TE resonance. Introduction Fluorescence-based biological assays are used widely for measurements in life-science research

Cunningham, Brian

191

No Compton Reflection In a Chandra/RXTE Observation of Mkn 509: Implications for the Fe-K Line Emission From Accreting X-Ray Sources  

NASA Technical Reports Server (NTRS)

We report the results of simultaneous Chandra and RXTE observations of the Seyfert 1 galaxy Mkn 509. We deconvolve the broad and narrow Fe-K emission-line components for which we measure rest-frame equivalent widths of 119+/-18 eV and 57+/-13 eV respectively. The broad line has a FWHM of 57,600((sup 14,400)(sub -21,000)) km/s and the narrow line is unresolved, with an upper limit on the FWHM of 4,940 km/s. Both components must originate in cool matter since we measure rest-frame center energies of 6.36((sup +0.13)(sub -0.12)) keV and 6.42+/-0.01 keV for the broad and narrow line respectively. This rules out He-like and H-like Fe for the origin of both the broad and narrow lines. If, as is widely accepted, the broad Fe-K line originates in Thomson-thick matter (such as an accretion disk), then one expects to observe spectral curvature above approximately 10 keV, (commensurate with the observed broad line), characteristic of the Compton-reflection continuum. However our data sets very stringent limits on deviations of the observed continuum from a power law. Light travel-time delays cannot be invoked to explain anomalies in the relative strengths of the broad Ferry line and Compton-reflection continuum since they are supposed to originate in the same physical location. We are forced to conclude that both the broad and narrow Fe-K lines had to originate in Thomson-thin matter during our observation. This result, for a single observation of just one source, means that our understanding of Fe K line emission and Compton reflection from accreting X-ray sources in general needs to be re-examined. For example, if an irradiated accretion disk existed in Mkn 509 at the time of the observations, the lack of spectral curvature above approximately 10 keV suggests two possibilities. Either the disk was Thomson-thick and highly ionized, having negligible Fe-K line emission and photoelectric absorption or the disk was Thomson-thin producing some or all of the broad Fe-K line emission. In the former case, the broad Fe-K line had to have produced in a Thomson-thin region elsewhere. In both cases the predicted spectral curvature above approximately 10 keV is negligible. An additional implication of our results is that any putative obscuring torus in the system, required by unification models of active galaxies, must also be Thomson-thin. The same applies to the optical broad line region (BLR) if it has a substantial covering factor.

Yaqoob, Tahir; Padmanabhan, Urmila; Kraemer, Steven B.; Crenshaw, D. Michael; Mckernan, Barry; George, Ian M.; Turner, T. Jane; White, Nicholas E. (Technical Monitor)

2002-01-01

192

GO FURTHER... EXCITING OPPORTUNITIES TO  

E-print Network

work ethic. ...YOU WILL ALSO MAKE LIFELONG FRIENDS... HAVE THE MOST MEMORABLE EXPERIENCES... AND ENJOY the website for full details. SEE HOW FAR YOU CAN GO... Availability varies every year. Check out the websitefront GO FURTHER... EXCITING OPPORTUNITIES TO AQUIRE INTERNATIONAL EXPERIENCE See how far you can

Martin, Ralph R.

193

Dissociation of Highly Excited Molecules  

NASA Astrophysics Data System (ADS)

A survey of the spectroscopy and dynamics of the dissociation of highly excited molecules is presented with emphasis on superexcited molecules by electron- and photon-impact.(See review articles: a) Y. Hatano, The Physics of Electronic and Atomic Collisions, eds., L. J. Dube et al., AIP Press, New York (1995) pp.67-88; b) N.Kouchi et al., J. Phys. B, 30, 2319 (1997); c) Y. Hatano, Dynamics of Excited Molecules, ed., K. Kuchitsu, Elsevier, Amsterdam (1994) Chapter 6.) Topics will include newly developed experimental methods covering two-dimensional spectroscopy of photodissociation(M. Ukai et al., Phys. Rev. Lett., 74, 239 (1995).) (S. Machida et al., J. Phys. Chem. A. 101, 656 (1997).) (A. Ehresmann et al., J. Phys. B, 29, 3629 (1996).), and coincident electron-energy-loss spectroscopy of the dissociation dynamics of highly excited molecules.(T. Odagiri et al., J. Phys. B, 28, L465 (1995).)(T. Odagiri et al., J. Phys. B, 29, 1829 (1996).) The measurement of absolute photoionization quantum yields will also be discussed.(K. Kameta et al., J. Chem. Phys., 99, 2487 (1993).) Comparative studies of electron- and photon-impact dissociative excitation of molecules will be summarized. The molecules studied are H_2, N_2, O_2, CO, CO_2, N_2O, hydrocarbons, and some Si-containing compounds.

Hatano, Yoshihiko

1997-10-01

194

Elementary Excitations in Quantum Liquids.  

ERIC Educational Resources Information Center

Discusses elementary excitations and their role in condensed matter physics, focusing on quantum plasma, helium liquids, and superconductors. Considers research primarily conducted in the 1950s and concludes with a brief survey of some closely related further developments. (Author/JN)

Pines, David

1981-01-01

195

QUASIPERIODIC RESPONSE TO PARAMETRIC EXCITATIONS  

E-print Network

are reduced to systems of Mathieu-type equations (Mathieu [21]). These reductions are strictly only possible, this excitation of the free surface is described by the Mathieu equation (1.1) ij + (02 +a sinwt) rJ = 0, where 0 flat, mean position. This equation of Mathieu [21] has been studied extensively (see for example Jordan

Marques, Francisco

196

Science and Science Fiction  

ERIC Educational Resources Information Center

This article is for teachers looking for new ways to motivate students, increase science comprehension, and understanding without using the old standard expository science textbook. This author suggests reading a science fiction novel in the science classroom as a way to engage students in learning. Using science fiction literature and language…

Oravetz, David

2005-01-01

197

Ab initio Optical Absorption by A Simple and Efficient Method: Single Excitation Configuration Interaction After Downfolding  

NASA Astrophysics Data System (ADS)

We present a simple and efficient ab initio method for calculating electronic excited states and optical absorption spectra of solids. The method is based on a single-excitation configuration-interaction calculation after downfolding to model Hamiltonians represented by maximally-localized Wannier functions. Single-excitation configurations are crucially important in evaluating a linear absorption, because they can describe a so-called excitonic effect; interactions in electron-hole pairs generated by excitations. A test was performed for a semiconductor GaAs, and detailed analyses for the resulting spectra and single-excitation many-body wavefunctions are presented. This work is supported by a Grant-in-Aid for Scientific Research in Priority Areas, ``Development of New Quantum Simulators and Quantum Design'' (No. 17064004) of the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Nakamura, Kazuma; Yoshimoto, Yoshihide; Arita, Ryotaro; Imada, Masatoshi; Tsuneyuki, Shinji

2007-03-01

198

Variability and Spectral Studies of Luminous Seyfert 1 Galaxy Fairall 9. Search for the Reflection Component is a Quasar: RXTE and ASCA Observation of a Nearby Radio-Quiet Quasar MR 2251-178  

NASA Technical Reports Server (NTRS)

Monitoring observations with interval of 3 days using RXTE (X Ray Timing Explorer) of the luminous Seyfert 1 galaxy Fairall 9 were performed for one year. The purpose of the observations were to study the variability of Fairall 9 and compare the results with those from the radio-loud object 3C 390.3. The data has been received and analysis is underway, using the new background model. An observation of the quasar MR 2251-178 was made in order to determine whether or not it has a reflection component. Older background models gave an unacceptable subtraction and analysis is underway using the new background model. The observation of NGC 6300 showed that the X-ray spectrum from this Seyfert 2 galaxy appears to be dominated by Compton reflection.

Leighly, Karen M.

1999-01-01

199

Search for Intrinsic Excitations in 152Sm  

E-print Network

The 685 keV excitation energy of the first excited 0+ state in 152Sm makes it an attractive candidate to explore expected two-phonon excitations at low energy. Multiple-step Coulomb excitation and inelastic neutron scattering studies of 152Sm are used to probe the E2 collectivity of excited 0+ states in this "soft" nucleus and the results are compared with model predictions. No candidates for two-phonon K=0+ quadrupole vibrational states are found. A 2+, K=2 state with strong E2 decay to the first excited K=0+ band and a probable 3+ band member are established.

W. D. Kulp; J. L. Wood; P. E. Garrett; C. Y. Wu; D. Cline; J. M. Allmond; D. Bandyopadhyay; D. Dashdorj; S. N. Choudry; A. B. Hayes; H. Hua; M. G. Mynk; M. T. McEllistrem; C. J. McKay; J. N. Orce; R. Teng; S. W. Yates

2008-05-13

200

Backreaction of excitations on a vortex  

E-print Network

Excitations of a vortex are usually considered in a linear approximation neglecting their backreaction on the vortex. In the present paper we investigate backreaction of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the backreaction corrections. Their approximate solutions are found in the cases of plane wave and wave packet type excitations. We find that the excited vortex radiates vector field and that the Higgs field has a very broad oscillating component.

Henryk Arodz; Leszek Hadasz

1996-07-15

201

Computer Science Teachers Association  

NSDL National Science Digital Library

The Computers Science Teachers Association (CSTA) is a professional organization that helps teachers in the field learn about professional development opportunities, along with offering them the opportunity to network. This section of then CSTA's website provides access to over a dozen helpful resources, including an instructional video and a college selection website. First-time visitors should check out the Quizzes with a Theme. Here they will find a set of computer science themed quizzes developed by Professor Bruce Maxwell of Colby College. Also, the CS Unplugged Videos area is quite a bit of fun. The videos here include a one-hour computer science show in which students encounter many concepts from computer science, along with short clips of activities that can be used in the classroom. Additionally, the site includes a selection of computer games designed for young women and a link to resources promoting excitement about computer science from Carnegie Mellon University.

202

Physical Science Earth Science  

E-print Network

Science Archaeology Future Thought Science & Society Conservation Ethics Investigative Research Philosophy the Georgia Tech Research Institute (GTRI) and the Indian Head Division of the Naval Surface Warfare Center

Bennett, Gisele

203

The Exciting World of Search and Discovery: Research Experiences as part of the Undergraduate Astronomy Curriculum  

NASA Astrophysics Data System (ADS)

The active participation of undergraduates in research has been one of the cornerstones of the Astronomy & Astrophysics program at Villanova University for over 30 years. When teamed with faculty researchers and involved with interesting projects that have the full attention and commitment of the faculty, the students not only greatly benefit and learn, but are able to make significant contributions to the research project. Every effort is made to attract the student's personal commitment to research projects, starting usually during the sophomore year. It has been found that once the student's interest is enkindled, the natural curiosity of the student usually sustains that interest. After this occurs, it is possible to move away from the traditional work for a grade mentality of a student to the more satisfying and fulfilling work for pleasure and the excitement of discovery that most successful researchers experience. This shift in attitude is important because it allows the students to tap into a block of time that they have mentally set aside as ``extra-curricular.'' Many students accompany faculty on external observing runs, attend professional meetings and present papers, and co-author papers and articles. When possible during the summer months, the students work as Research Assistants and are paid by the university or from NASA or NSF grants. All of the faculty in the Astronomy Department participate in the research projects with the undergraduate students. This gives the students a choice of a wide range of research topics. Typically research projects are based on photoelectric photometry (mostly of pulsating, spotted, PMS, and eclipsing binary stars) obtained by student observations on campus or with a 0.8m APT located in Arizona. Many interesting and productive research programs on cataclysmic variables, symbiotic stars, and chromospherically active stars also utilize archival data available from IUE, HST, FUSE, RXTE and ROSAT. Since 1990 over 45 students have participated in research projects that have resulted in papers in journals or at professional meetings (such as the AAS).

Guinan, E. F.

2003-12-01

204

Excitable behaviour in amoeboid chemotaxis  

PubMed Central

Chemotaxis, the directed motion of cells in response to chemical gradients, is a fundamental process. Eukaryotic cells detect spatial differences in chemoattractant receptor occupancy with high precision and use these differences to bias the location of actin-rich protrusions to guide their movement. Research into chemotaxis has benefitted greatly from a systems biology approach that combines novel experimental and computational tools to pose and test hypothesis. Recently, one such hypothesis has been postulated proposing that chemotaxis in eukaryotic cells is mediated by locally biasing the activity of an underlying excitable system. The excitable system hypothesis can account for a number of cellular behaviours related to chemotaxis, including the stochastic nature of the movement of unstimulated cells, the directional bias imposed by chemoattractant gradients, and the observed spatial and temporal distribution of signalling and cytoskeleton proteins. PMID:23757165

Shi, Changji

2013-01-01

205

Solitonlike excitations in biological systems  

NASA Astrophysics Data System (ADS)

A model for solitonlike excitation in DNA is presented and assessed in the context of previous models of collective excitations in other biological systems. A qualitative analysis describes the mechanisms of some DNA function, in particular opening of DNA base pairs to initiate protein synthesis. A formalism is presented which analyzes quantitatively the above-mentioned model, predicts the threshold for B-DNA-->A-DNA transition, and specifies the parameters of particular electromagnetic stimulations that can produce or initiate a variety of DNA responses and effects. The example of insulin production is discussed in detail and theoretical predictions are given for the parameters of an electromagnetic signal reproducing the stimulation to a cell which would lead to insulin production as a response.

Balanovski, Eduardo; Beaconsfield, Peter

1985-11-01

206

Excitation transport through Rydberg dressing  

NASA Astrophysics Data System (ADS)

We show how to create long-range interactions between alkali atoms in different hyperfine ground states, with the goal of coherent quantum transport. The scheme uses off-resonant dressing with atomic Rydberg states. We demonstrate coherent migration of electronic excitation through dressed dipole-dipole interaction by full solutions of models with four essential states per atom and give the structure of the spectrum of dressed states for a dimer. In addition, we present an effective (perturbative) Hamiltonian for the ground-state manifold and show that it correctly describes the full multi-state dynamics. We discuss excitation transport in detail for a chain of five atoms. In the presented scheme, the actual population in the Rydberg state is kept small. Dressing offers many advantages over the direct use of Rydberg levels: it reduces ionization probabilities and provides an additional tuning parameter for lifetimes and interaction strengths.

Wüster, S.; Ates, C.; Eisfeld, A.; Rost, J. M.

2011-07-01

207

Coulomb excitation and transfer reactions  

NASA Astrophysics Data System (ADS)

Using the ?-spectrometer GASP and the PYRAMID array of position sensitive particle counters enabled improved nuclear structure studies employing direct reactions. Coulomb excitation of 232Th by 58Ni at a beam energy of 265 MeV was used to investigate multi-phonon surface vibrations. For 232Th a new band has been found which is interpreted as harmonic two-phonon octupole vibrational band with K ?=0 +. The system 110Pd + 52Cr was chosen to study the mechanism of multinucleon transfer at energies in the vicinity of the Coulomb barrier. It was possible to identify 10 different transfer channels by their characteristic ?-decay. The total excitation energy versus ?-multiplicity correlations for the most prominent even-even transfer channels show a ‘cold’ component which is a strong indication for correlated pair transfer. For the 2n and 2p channel this fraction is 30(4)%, respectively 16(8)%.

Gerl, J.; Bazzacco, D.; Elze, Th. W.; Happ, T.; Härtlein, T.; Korten, W.; Kröll, T.; Napoli, D.; Alvarez, C. Rossi; Schubert, R.; Vetter, K.; Wollersheim, H. J.

208

The rhythm of cortical excitability.  

PubMed

Evidence has been gained which suggests that the spectral properties of the excitability cycle are other than those first proposed or assumed to exist in a number of experiments and theories. Instead of appearing as a sinusoidal cycle at the alpha frequency, the excitability cycle seems to be irregular and slower on the average than the EEG alpha rhythm. The rhythm appears to be continuously operative. It is not very sensitive in its spectral composition to the conditions of illumination or the level of behavioral activity. The rhythm operates synchronously in the right and left visual cortex. Methods similar to those described here could be used to map the extent to which synchrony is maintained in structures throughout the brain. They also suggest new approaches for psycho-physical studies which are aimed at establishing relationships between behavioral or perceptual phenomena and measures of neural activity. PMID:6159153

Rudell, A

1980-07-01

209

Continuum excitations in 6He  

Microsoft Academic Search

The three-body breakup 6He-->4He+n+n is studied experimentally, using a secondary 6He ion beam of 240 MeV\\/nucleon incident on carbon and lead targets. Integrated cross sections for one- and two-neutron knockout and differential cross sections dsigma\\/dE* and dsigma\\/dvartheta for inelastic nuclear or electromagnetic excitations into the 6He continuum are presented. The E1-strength distribution is deduced from electromagnetic cross sections and is

T. Aumann; D V Aleksandrov; L. Axelsson; T. Baumann; M. J. Borge; L. V. Chulkov; J. Cub; W. Dostal; B. Eberlein; Th. W. Elze; H. Emling; H. Geissel; V. Z. Goldberg; M S Golovkov; A Grünschloss; M. Hellström; K. Hencken; J. Holeczek; R. Holzmann; B. Jonson; A. A. Korshenninikov; J. V. Kratz; G. Kraus; R. Kulessa; Y. Leifels; A. Leistenschneider; T E Leth; I. Mukha; G. Münzenberg; F. Nickel; T. Nilsson; G H Nyman; B. Petersen; M. Pfützner; A. Richter; K. Riisager; C. Scheidenberger; G. Schrieder; W. Schwab; H. Simon; M. H. Smedberg; M. Steiner; J. Stroth; A. Surowiec; T. Suzuki; O. Tengblad; M. V. Zhukov

1999-01-01

210

On Diversity of Configurations Generated by Excitable Cellular Automata with Dynamical Excitation Intervals  

NASA Astrophysics Data System (ADS)

Excitable cellular automata with dynamical excitation interval exhibit a wide range of space-time dynamics based on an interplay between propagating excitation patterns which modify excitability of the automaton cells. Such interactions leads to formation of standing domains of excitation, stationary waves and localized excitations. We analyzed morphological and generative diversities of the functions studied and characterized the functions with highest values of the diversities. Amongst other intriguing discoveries we found that upper boundary of excitation interval more significantly affects morphological diversity of configurations generated than lower boundary of the interval does and there is no match between functions which produce configurations of excitation with highest morphological diversity and configurations of interval boundaries with highest morphological diversity. Potential directions of future studies of excitable media with dynamically changing excitability may focus on relations of the automaton model with living excitable media, e.g. neural tissue and muscles, novel materials with memristive properties and networks of conductive polymers.

Adamatzky, Andrew

2012-12-01

211

Vibrationally excited hydroxyl tagging velocimetry.  

PubMed

A new molecular-based velocity method is developed for high-temperature flame gases based on the hydroxyl tagging velocimetry (HTV) technique. In vibrationally excited HTV (VE-HTV), two photons from a KrF laser (248 nm) dissociate H2O into a tag line of vibrationally excited OH (v=1). The excited state OH tag is selectively detected in a background of naturally occurring ground state OH (v=0). In atmospheric pressure laboratory burners, the OH (v=1) tag persists for 5-10 ?s, allowing single-shot velocity measurements along a 2 cm line under lean, stoichiometric, and rich flame conditions with temperatures reaching 2300 K. Mean velocity measurements are demonstrated in a lean (?=0.78) premixed H2/air turbulent flame (Re=26,550) laboratory flame. The VE-HTV method is best suited to measure high-speed velocities in hot combustion environments in the presence of background OH. PMID:25402874

Grady, Nathan; Pitz, Robert W

2014-11-01

212

Self-excited multifractal dynamics  

NASA Astrophysics Data System (ADS)

We introduce the self-excited multifractal (SEMF) model, defined such that the amplitudes of the increments of the process are expressed as exponentials of a long memory of past increments. The principal novel feature of the model lies in the self-excitation mechanism combined with exponential nonlinearity, i.e. the explicit dependence of future values of the process on past ones. The self-excitation captures the microscopic origin of the emergent endogenous self-organization properties, such as the energy cascade in turbulent flows, the triggering of aftershocks by previous earthquakes and the "reflexive" interactions of financial markets. The SEMF process has all the standard stylized facts found in financial time series, which are robust to the specification of the parameters and the shape of the memory kernel: multifractality, heavy tails of the distribution of increments with intermediate asymptotics, zero correlation of the signed increments and long-range correlation of the squared increments, the asymmetry (called "leverage" effect) of the correlation between increments and absolute value of the increments and statistical asymmetry under time reversal.

Filimonov, V.; Sornette, D.

2011-05-01

213

Two-photon excitation of aluminium phthalocyanines  

SciTech Connect

A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined. (lasers in medicine)

Meshalkin, Yu P; Alfimov, E E; Makukha, V K [Novosibirsk State Technical University, Novosibirsk (Russian Federation); Vasil'ev, N E; Denisov, A N; Ogirenko, A P [Siberian Laser Medicine Centre, Novosibirsk (Russian Federation)

1999-12-31

214

Excited Quark Production at Future p Colliders  

Microsoft Academic Search

Excited quark production at future p colliders is studied. Namely, p ! q?X with subsequent q? ! gq and q decay channels are considered. Signatures for discovery of the excited quark and corresponding standard model backgrounds are discussed in detail. Discovery limits for excited quark masses and achievable values of compositeness parameters fs, f and fare determined.

R. Ciftci

215

Goddard's Astrophysics Science Division Annual Report 2011  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division(ASD) at Goddard Space Flight Center(GSFC)is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radiowavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contract imaging techniques to serch for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, and provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and suppport the astronomical community, and enable future missions by conceiving new conepts and inventing new technologies.

Centrella, Joan; Reddy, Francis; Tyler, Pat

2012-01-01

216

The Astrophysics Science Division Annual Report 2009  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum - from gamma rays to radio wavelengths - as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions - WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contrast imaging techniques to search for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical community, and enable future missions by conceiving new concepts and inventing new technologies.

Oegerle, William (Editor); Reddy, Francis (Editor); Tyler, Pat (Editor)

2010-01-01

217

Science and Science Fiction  

NSDL National Science Digital Library

This creative activity weaves science fiction and language arts skills into the science classroom, which can expand and enrich the science content and abstract concepts found in science textbooks.Well-written literature can be used to open new ways of learning and understanding while developing critical thinking skills for students of all abilities.

Oravetz, David

2005-03-01

218

Theoretical studies of electronically excited states  

NASA Astrophysics Data System (ADS)

Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploitingmethods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

Besley, Nicholas A.

2014-10-01

219

Topology regulates the distribution pattern of excitations in excitable dynamics on graphs  

NASA Astrophysics Data System (ADS)

We study the average excitation density in a simple model of excitable dynamics on graphs and find that this density strongly depends on certain topological features of the graph, namely connectivity and degree correlations, but to a lesser extent on the degree distribution. Remarkably, the average excitation density is changed via the distribution pattern of excitations: An increase in connectivity induces a transition from globally to locally organized excitations and, as a result, leads to an increase in the excitation density. A similar transition can be induced by increasing the rate of spontaneous excitations while keeping the graph architecture constant.

Müller-Linow, Mark; Marr, Carsten; Hütt, Marc-Thorsten

2006-07-01

220

Sloshing motions in excited tanks  

NASA Astrophysics Data System (ADS)

A fully non-linear finite difference model has been developed based on inviscid flow equations. Numerical experiments of sloshing wave motion are undertaken in a 2-D tank which is moved both horizontally and vertically. Results of liquid sloshing induced by harmonic base excitations are presented for small to steep non-breaking waves. The simulations are limited to a single water depth above the critical depth corresponding to a tank aspect ratio of hs/ b=0.5. The numerical model is valid for any water depth except for small depth when viscous effects would become important. Solutions are limited to steep non-overturning waves. Good agreement for small horizontal forcing amplitude is achieved between the numerical model and second order small perturbation theory. For large horizontal forcing, non-linear effects are captured by the third-order single modal solution and the fully non-linear numerical model. The agreement is in general good, both amplitude and phase. As expected, the third-order compared to the second-order solution is more accurate. This is especially true for resonance, high forcing frequency and mode interaction cases. However, it was found that multimodal approximate forms should be used for the cases in which detuning effects occur due to mode interaction. We present some test cases where detuning effects are evident both for single dominant modes and mode interaction cases. Furthermore, for very steep waves, just before the waves overturn, and for large forcing frequency, a discrepancy in amplitude and phase occurs between the approximate forms and the numerical model. The effects of the simultaneous vertical and horizontal excitations in comparison with the pure horizontal motion and pure vertical motion is examined. It is shown that vertical excitation causes the instability associated with parametric resonance of the combined motion for a certain set of frequencies and amplitudes of the vertical motion while the horizontal motion is related to classical resonance. It is also found that, in addition to the resonant frequency of the pure horizontal excitation, an infinite number of additional resonance frequencies exist due to the combined motion of the tank. The dependence of the non-linear behaviour of the solution on the wave steepness is discussed. It is found that for the present problem, non-linear effects become important when the steepness reaches about 0.1, in agreement with the physical experiments of Abramson [Rep. SP 106, NASA, 1966].

Frandsen, Jannette B.

2004-05-01

221

Some mathematical problems of excitability.  

PubMed

The description of the electrical behaviour of nerve and muscle is one of the most quantitative areas of cellular physiology. There are detailed biophysical measurements of currents and potentials, that may be summarised as Master equations or stochastic differential equations for membrane channel and noise recordings, and nonlinear differential equations for macroscopic voltage clamp recordings. Propagation in excitable media is described by nonlinear reaction-diffusion equations. Computational approaches can provide solutions to these equations, but without qualitative studies on simplified caricatures contribute little to mathematical or physiological understanding. PMID:2082914

Holden, A V

1990-01-01

222

New Modes of Nuclear Excitations  

NASA Astrophysics Data System (ADS)

We present a theoretical approach based on density functional theory supplemented by a microscopic multi-phonon model which is applied for investigations of pygmy resonances and other excitations of different multipolarities in stable and exotic nuclei. The possible relation of low-energy modes to the properties of neutron or proton skins is systematically studied in isotonic and isotopic chains. The fine structure of nuclear electric and magnetic response functions is analyzed and compared to experimental data. Their relevance to nuclear astrophysics is discussed.

Tsoneva, Nadia; Lenske, Horst

2014-03-01

223

Entropy Driven Atomic Motion in Laser-Excited Bismuth  

SciTech Connect

We introduce a thermodynamical model based on the two-temperature approach in order to fully understand the dynamics of the coherent A{sub 1g} phonon in laser-excited bismuth. Using this model, we simulate the time evolution of (111) Bragg peak intensities measured by Fritz et al.[Science 315, 633 (2007)] in femtosecond x-ray diffraction experiments performed on a bismuth film for different laser fluences. The agreement between theoretical and experimental results is striking not only because we use fluences very close to the experimental ones but also because most of the model parameters are obtained from ab initio calculations performed for different electron temperatures.

Giret, Y.; Gelle, A.; Arnaud, B. [Institut de Physique de Rennes (IPR), UMR UR1-CNRS 6251, Campus de Beaulieu-Bat 11 A, 35042 Rennes Cedex, France, EU (France)

2011-04-15

224

Dual excitation multiphase electrostatic drive  

SciTech Connect

A novel electrostatic drive technology named Dual Excitation Multiphase Electrostatic Drive (DEMED) was presented. A basic DEMED consisted of two plastic films in which 3-phase parallel electrodes were embedded and was driven by a 3-phase ac excitation to the electrodes. Static characteristics of DEMED were calculated and tested and the results agreed very well. Three prototype motors of DEMED were fabricated using commercially available technique. The first prototype consisted of a single slider and stator and generated a linear motion with a slider`s motion range of about 5mm. It weighed 7g and generated a power of 1.6W and a thrust force of 4.4N. The second prototype consisted of 50 layer stack of linear motors, summing their outputs. It weighed 3.6kg and generated a propulsive force of 310N being powered with boosted commercial 3-phase electricity. The third prototype consisted of a rotor and a stator in which electrodes were arranged radially and generated rotational motion. The maximum power of 36mW was generated by the prototype weighing only 260mg for its rotor and stator. From the results of the numerical calculation, a practical design methodology for the motor was determined. An optimal design for a motor employing currently available material and fabrication techniques is provided as an example. Analyses predict that force generation over the interfacial area between the slider and stator of this motor would be 3,900N/m{sup 2}.

Niino, Toshiki [Inst. of Physical and Chemical Research, Wako, Saitama (Japan); Higuchi, Toshiro [Univ. of Tokyo (Japan); [Kanagawa Academy of Science and Technology, Kawasaki, Kanagawa (Japan); Egawa, Saku [Hitachi Ltd., Tsuchiura, Ibaraki (Japan). Mechanical Engineering Research Lab.

1995-12-31

225

4 Science_ gervice Nature .Released upon receipt  

E-print Network

4 Science_ gervice Nature .Released upon receipt but intended for use A p r i l 18, 1933 3 up a good deal Qf popular excite- ment, affording an illustration of the fact that while halos have be identified as the rea3 moon plus four moondogs, or paraselenae -- members of the halo family -- but science

226

Oregon Health & Science University School of Medicine  

E-print Network

. With this in mind, interprofessional education is another important aspect of medical education. We striveOregon Health & Science University School of Medicine Medical Student Handbook 2012-2013 #12;Oregon Health & Science University School of Medicine Medical Student Handbook Welcome This is an exciting time

Chapman, Michael S.

227

Oregon Health & Science University School of Medicine  

E-print Network

. With this in mind, interprofessional education is another important aspect of medical education. We striveOregon Health & Science University School of Medicine Medical Student Handbook 2011-2012 #12;Oregon Health & Science University School of Medicine Medical Student Handbook Welcome This is an exciting time

Chapman, Michael S.

228

Exciting Times Call for Collaboration  

ERIC Educational Resources Information Center

Brain science already has much to contribute to education and will become even more important in the future. Brain research is not going away; it is increasing and will continue to do so. As such, educators need better tools to deal with it. In this article, the author argues that educators desperately need new understandings, new ways to think…

Jensen, Eric P.

2008-01-01

229

Excited state intramolecular charge transfer reaction in nonaqueous electrolyte solutions: Temperature dependence  

E-print Network

: Temperature dependence Tuhin Pradhan, Harun Al Rasid Gazi, and Ranjit Biswasa Department of Chemical, Biological and Macromolecular Sciences and Unit for Nanoscience and Technology, S. N. Bose National Centre; accepted 15 July 2009; published online 6 August 2009 Temperature dependence of the excited state

Biswas, Ranjit

230

Public Engagement in the Science of NLSI's Center for Lunar Origin and Evolution (CLOE)  

NASA Astrophysics Data System (ADS)

The Center for Lunar Origin and Evolution (CLOE) team is sharing CLOE research about the Moon’s formation and evolution, NLSI science, and excitement about space science with high-school students and the general public.

Laconte, K.; Shupla, C.; Barr, A.; Shipp, S.; Bottke, W. F.

2012-03-01

231

SCIENCE CHINA Technological Sciences  

E-print Network

SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg) · RESEARCH PAPER · February 2012 Vol.55 No.2: 568­580 doi: 10.1007/s11431-011-4643-2 Coupling of wave This paper presents 2D wave-current interaction model for evaluating nearly horizontal wave-induced currents

US Army Corps of Engineers

232

arts science The College of  

E-print Network

our many talented people, gives everyone in the College an opportunity to nominate an outstanding1spring arts science The College of spring 2009 Ron Wheeler's Lesson in Terrorism Wrangling as Dean of this College four years ago, and it has been very exciting to see many of these projects now

Saskatchewan, University of

233

Final excitation energy of fission fragments  

SciTech Connect

We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission, where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition in statistical equilibrium for different level-density descriptions as a function of the total intrinsic excitation energy of the fissioning system. Excitation energies are found to be strongly enhanced in the heavy fragment, if the level density follows a constant-temperature behavior at low energies, e.g., in the composed Gilbert-Cameron description.

Schmidt, Karl-Heinz; Jurado, Beatriz [Centre d'Etudes Nucleaires de Bordeaux Gradignan (CENBG), CNRS/IN2P3, Chemin du Solarium, B.P. 120, F-33175 Gradignan (France)

2011-06-15

234

PHYSICAL REVIEW B VOLUME 41, NUMBER 7 1 MARCH 1990 Temperature dependence of the phonon and roton excitations in liquid He  

E-print Network

, University ofKeele, Keele ST5 5BG, United Kingdom and Science and Engineering Research Counci I, Daresbury in the "phonon" and "roton" regions, respectively, of the single excitation dispersion curve of the superfluid

Glyde, Henry R.

235

Search for excited neutrinos in Z decay  

NASA Astrophysics Data System (ADS)

Excited neutrinos decaying into a neutrino and a photon are searched for in the ALEPH detector at LEP. No evidence is found for Z decay into v¯v ? or v¯ ?v ? final states. Upper limits are derived on excited neutrino couplings up to excited neutrino masses close to the Z mass. Lower limits on the v ? mass, independent of the v ? decay modes, are deduced from the total Z width.

Decamp, D.; Deschizeaux, B.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Alemany, R.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Gaitan, V.; Garrido, Ll.; Mato, P.; Miguel, R.; Mir, Ll. M.; Orteu, S.; Pacheco, A.; Perlas, J. A.; Tubau, E.; Catanesi, M. G.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Maggi, M.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Gao, Y.; Hu, H.; Huang, D.; Jin, S.; Lin, J.; Ruan, T.; Wang, T.; Wu, W.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhao, W.; Atwood, W. B.; Bird, F.; Blucher, E.; Bonvicini, G.; Bossi, F.; Bourotte, J.; Brown, D.; Burnett, T. H.; Drevermann, H.; Dydak, F.; Forty, R. W.; Grab, C.; Hagelberg, R.; Haywood, S.; Jost, B.; Kasemann, M.; Kellner, G.; Knobloch, J.; Lacourt, A.; Lehraus, I.; Lohse, T.; Marchioro, A.; Martinez, M.; Menary, S.; Minten, A.; Miotto, A.; Nash, J.; Palazzi, P.; Ranjard, F.; Redlinger, G.; Roth, A.; Rothberg, J.; Rotscheidt, H.; von Rüden, W.; St. Denis, R.; Schlatter, D.; Takashima, M.; Talby, M.; Taureg, H.; Tejessy, W.; Wachsmuth, H.; Wasserbaech, S.; Wheeler, S.; Wiedenmann, W.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Bardadin-Otwinowska, M.; Falvard, A.; El Fellous, R.; Gay, P.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Proriol, J.; Prulhière, F.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nilsson, B. S.; Petersen, G.; Efthymiopoulos, I.; Simopoulou, E.; Vayaki, A.; Badier, J.; Blondel, A.; Bonneaud, G.; Braems, F.; Brient, J. C.; Fouque, G.; Gamess, A.; Guirlet, R.; Rosowsky, A.; Rougé, A.; Rumpf, M.; Tanaka, R.; Videau, H.; Videau, I.; Candlin, D. J.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Lannutti, J.; Levinthal, D.; Mermikides, M.; Sawyer, L.; Stimpfl, G.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Campana, P.; Capon, G.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Massimo-Brancacci, F.; Murtas, F.; Murtas, G. P.; Nicoletti, G.; Pepe-Altarelli, M.; Picchi, P.; Zografou, P.; Altoon, B.; Boyle, O.; Halley, A. W.; Ten Have, I.; Hearns, J. L.; Lynch, J. G.; Morton, W. T.; Raine, C.; Scarr, J. M.; Smith, K.; Thompson, A. S.; Brandl, B.; Braun, O.; Geiges, R.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Belk, A. T.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Dornan, P. J.; Dugeay, S.; Greene, A. M.; Hassard, J. F.; Patton, S. J.; Sedgbeer, J. K.; Taylor, G.; Tomalin, I. R.; Wright, A. G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Keemer, N. R.; Nuttall, M.; Rowlingson, B. S.; Sloan, T.; Snow, S. W.; Barczewski, T.; Bauerdick, L. A. T.; Kleinknecht, K.; Renk, B.; Roehn, S.; Sander, H.-G.; Schmelling, M.; Steeg, F.; Albanese, J.-P.; Aubert, J.-J.; Benchouk, C.; Bernard, V.; Bonissent, A.; Courvoisier, D.; Etienne, F.; Papalexiou, S.; Payre, P.; Pietrzyk, B.; Qian, Z.; Blum, W.; Cattaneo, P.; Cowan, G.; Dehning, B.; Dietl, H.; Fernandez-Bosman, M.; Jahn, A.; Lange, E.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Pan, Y.; Richter, R.; Schwarz, A. S.; Settles, R.; Stiegler, U.; Stierlin, U.; Thomas, J.; Bertin, V.; de Bouard, G.; Boucrot, J.; Callot, O.; Chen, X.; Cordier, A.; Davier, M.; Ganis, G.; Grivaz, J.-F.; Heusse, Ph.; Janot, P.; Journé, V.; Kim, D. W.; Lefrançois, J.; Lutz, A.-M.; Veillet, J.-J.; Zhang, Z.; Zomer, F.; Amendolia, S. R.; Bagliesi, G.; Batignani, G.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Ciocci, M. A.; Ferrante, I.; Fidecaro, F.; Foà, L.; Focardi, E.; Forti, F.; Giassi, A.; Giorgi, M. A.; Ligabue, F.; Lusiani, A.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Carter, J. M.; Green, M. G.; March, P. V.; Medcalf, T.; Saich, M. R.; Strong, J. A.; Thomas, R. M.; Wildish, T.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Edwards, M.; Fisher, S. M.; Harvey, J.; Jones, T. J.; Norton, P. R.; Salmon, D. P.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Klopfenstein, C.; Lançon, E.; Locci, E.; Loucatos, S.; Mirabito, L.; Monnier, E.; Perez, P.; Perrier, F.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Ashman, J. G.; Booth, C. N.; Combley, F.; Dinsdale, M.; Martin, J.; Parker, D.; Thompson, L. F.; Brandt, S.; Burkhardt, H.; Grupen, C.; Meinhard, H.; Neugebauer, E.; Schäfer, U.; Seywerd, H.; Apollinari, G.; Giannini, G.; Gobbo, B.; Liello, F.; Milotti, E.; Rolandi, L.; Bellantoni, L.; Boudreau, J. F.; Cinabro, D.; Conway, J. S.; Cowen, D. F.; Deweerd, A. J.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Harton, J. L.; Hilgart, J.

1990-11-01

236

Design evaluation: S-band exciters  

NASA Technical Reports Server (NTRS)

A design evaluation study was conducted to produce S-band exciter (SBE) system to provide a highly stable phase or modulated carrier for transmission to spacecraft. The exciter is part of an S-band receiver/exciter/ranging system at Spaceflight Tracking and Data Network (STDN) ground stations. The major features of the system are defined. Circuit diagrams of the electronic components are provided.

1974-01-01

237

Rydberg excitation of Bose-Einstein condensates  

E-print Network

Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations.

Rolf Heidemann; Ulrich Raitzsch; Vera Bendkowsky; Björn Butscher; Robert Löw; Tilman Pfau

2007-10-30

238

NASA Science Served Family Style  

NASA Astrophysics Data System (ADS)

Family oriented innovative programs extend the reach of many traditional out-of-school venues to involve the entire family in learning in comfortable and fun environments. Research shows that parental involvement is key to increasing student achievement outcomes, and family-oriented programs have a direct impact on student performance. Because families have the greatest influence on children's attitudes towards education and career choices, we have developed a Family Science program that provides families a venue where they can explore the importance of science and technology in our daily lives by engaging in learning activities that change their perception and understanding of science. NASA Family Science Night strives to change the way that students and their families participate in science, within the program and beyond. After three years of pilot implementation and assessment, our evaluation data shows that Family Science Night participants have positive change in their attitudes and involvement in science.  Even after a single session, families are more likely to engage in external science-related activities and are increasingly excited about science in their everyday lives.  As we enter our dissemination phase, NASA Family Science Night will be compiling and releasing initial evaluation results, and providing facilitator training and online support resources. Support for NASA Family Science Nights is provided in part through NASA ROSES grant NNH06ZDA001N.

Noel-Storr, Jacob; Mitchell, S.; Drobnes, E.

2010-01-01

239

Science Poetry in Two Voices: Poetry and the Nature of Science  

ERIC Educational Resources Information Center

Poetry can be used during science instruction to foster interest, excitement, and wonder among elementary-level students. Children can read poetry, or have poetry read to them, as a way of learning about their world. They can also create poems to share their own science learning with others. We introduce two formats of the Poetry in Two Voices…

Frazier, Wendy M.; Murray, Kristen B.

2009-01-01

240

Excitation of helium ion by positron impact  

SciTech Connect

Three (1s,2s,2p) and five (1s,2s,2p,3s-bar,3p-bar) -state close-coupling methods have been employed to calculate the n = 2 excitation cross sections of helium ion by positron impact. The effect of pseudostate is found to be very pronounced in the case of 1s-2s excitation.

Khan, P.; Ghosh, A.S.

1986-01-01

241

Laser-excited synchronous luminescence spectroscopy  

Microsoft Academic Search

The use of lasers as excitation sources for molecular luminescence often results in improvements in sensitivity and limits of detection (LODs). Synchronous luminescence (SL) spectroscopy, in which both excitation and emission wavelengths are scanned simultaneously, provides a convenient means to improve selectivity (often dramatically) in the analysis of multicomponent mixtures using room-temperature luminescence. The authors report here on the first

Christopher L. Stevenson; Tuan Vo-Dinh

1993-01-01

242

Vibrationally Excited Molecular Hydrogen near Herschel 36  

NASA Astrophysics Data System (ADS)

We present the first high resolution UV spectra toward Herschel 36, a Trapezium-like system of high-mass stars contained within the Lagoon Nebula (M8, NGC 6523). The spectra reveal extreme rovibrational excitation of molecular hydrogen in material at a single velocity or very small range of velocities, with this component presumably lying near the star system and undergoing fluorescent excitation. The overall H2 excitation is similar to, but apparently larger than, that seen toward HD 37903 which previously showed the largest vibrationally excited H2 column densities seen in UV absorption spectra. While the velocities of the highly excited H2 lines are consistent within each observation, it appears that they underwent a ~60 km s-1 redshift during the 3.6 yr between observations. In neither case does the velocity of the highly excited material match the velocity of the bulk of the line-of-sight material which appears to mostly be in the foreground of M8. Recent work shows unusually excited CH and CH+ lines and several unusually broad diffuse interstellar bands toward Herschel 36. Along with the H2 excitation, all of these findings appear to be related to the extreme environment within ~0.1 pc of the massive young stellar system.

Rachford, Brian L.; Snow, Theodore P.; Ross, Teresa L.

2014-05-01

243

Higgs type excitations in cold atom systems  

NASA Astrophysics Data System (ADS)

Higgs type excitations are the excitations which give mass to particles. The Higgs type excitations has a critical role both in particle physics and condensed matter physics. In particle physics, the suspected Higgs boson has been found by the Large Hadron Collider (LHC) in 2012. In condensed matter physics, the Higgs type excitations relate to order phase of the system. In this review, we present an overview of recent studies on the Higgs type excitations both in non-interacting and interacting cold atom systems. First, in non-interacting cold atom system, by synthesizing artificial non-Abelian gauge potential, we demonstrate that when a non-Abelian gauge potential is reduced to Abelian potential, the Abelian part constructs spin-orbit coupling, and the non-Abelian part emerges Higgs excitations. Secondly, the Higgs excitations which are the reputed Higgs amplitude mode in interacting cold atom system are discussed. We review the theoretical model and the experimental detection of Higgs amplitude mode in two dimensional superfluid. The observation of both Higgs type excitations in real experiments are also discussed.

Huang, FeiJie; Chen, QiHui; Liu, WuMing

2013-12-01

244

Multiphoton excited fluorescence spectroscopy of biomolecular systems  

Microsoft Academic Search

Recent work on the emerging application of multiphoton excitation to fluorescence studies of biomolecular dynamics and structure is reviewed. The fundamental principles and experimental techniques of multiphoton excitation are outlined, fluorescence lifetimes, anisotropy and spectra in membranes, proteins, hydrocarbons, skin, tissue and metabolites are featured, and future opportunities are highlighted.

David J. S. Birch

2001-01-01

245

Excited States of Non-Isolated Chromophores  

NASA Astrophysics Data System (ADS)

The photophysical and photochemical behavior of nucleobases is very important because of their biological role as the building blocks in DNA and RNA. Great progress has been made in understanding the excited-state properties of single bases. In order to understand the photophysical properties of nucleobases in complex environments we have investigated their excited states (a) in aqueous solutions and (b) as ?-stacked dimers in DNA. The solvatochromic shifts of the excited states of pyrimidine nucleobases in aqueous solution have been investigated using a combined QM/MM procedure where the quantum mechanical solute is described using high level multireference configuration interaction methods while molecular dynamics simulations are used to obtain the structure of the solvent around the solute in an average way. The excited states of ?-stacked nucleobases have also been investigated using various ab initio methods. The effect of the environment on the excited states and conical intersections is investigated.

Matsika, S.; Kozak, C.; Kistler, K.

2009-06-01

246

Discharge excitation of dye vapors  

NASA Astrophysics Data System (ADS)

Experiments have been conducted to assess the feasibility of obtaining a discharge-pumped dye vapor laser. A 15 (or 50) cm active length, UV-preionized device has been developed which exhibits a specific power loading of the medium of approx. 5 MW/cu cm and will operate continuously at temperatures exceeding 400 C. Recently, hydrogen thyratron switching of the device and corona preionization have been installed to minimize jitter and dye fragmentation. Optimization of the rare gas/N2 diluent mixture has been completed and fragmentation studies for several dye molecules have been conducted. POPOP and alpha-NPO are excellent in the latter regard but Coumarin 6 rapidly decomposes in the discharge environment. The fluorescence efficiency of alpha-NPO is only 40 percent of that for POPOP under comparable conditions. BBO and PBBO are similar in structure and molecular weight to POPOP and appear to be excellent candidates for discharge excitation. Fluorescence and small signal gain measurements are in progress.

Eden, J. G.

1987-09-01

247

Company: Mad Science of West New Jersey Work Location: North Brunswick and surrounding areas  

E-print Network

and managing a classroom while spreading the love of science to children who are eager to learn. Qualifications to excite children and convey to them that science surrounds them. We accomplish this by relating science personality, and experience with children, and minimum high school level science. Number of Openings: How

Hanson, Stephen José

248

Impact of ground- and excited-state aromaticity on cyclopentadiene and silole excitation energies and excited-state polarities.  

PubMed

A new qualitative model for estimating the properties of substituted cyclopentadienes and siloles in their lowest ??* excited states is introduced and confirmed through quantum chemical calculations, and then applied to explain earlier reported experimental excitation energies. According to our model, which is based on excited-state aromaticity and antiaromaticity, siloles and cyclopentadienes are cross-hyperconjugated "aromatic chameleons" that adapt their electronic structures to conform to the various aromaticity rules in different electronic states (Hückel's rule in the ?(2) electronic ground state (S0) and Baird's rule in the lowest ??* excited singlet and triplet states (S1 and T1)). By using pen-and-paper arguments, one can explain polarity changes upon excitation of substituted cyclopentadienes and siloles, and one can tune their lowest excitation energies by combined considerations of ground- and excited-state aromaticity/antiaromaticity effects. Finally, the "aromatic chameleon" model can be extended to other monocyclic compound classes of potential use in organic electronics, thereby providing a unified view of the S0, T1, and S1 states of a range of different cyclic cross-?-conjugated and cross-hyperconjugated compound classes. PMID:25043523

Jorner, Kjell; Emanuelsson, Rikard; Dahlstrand, Christian; Tong, Hui; Denisova, Aleksandra V; Ottosson, Henrik

2014-07-21

249

Science Mathematics Engineering  

E-print Network

Science Mathematics Engineering . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', Mathematics, . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', Mathematics, and Software Development

Hamlet, Richard

250

Practicing Science: The Investigative Approach in College Science Teaching  

NSDL National Science Digital Library

In this collection of ten articles reprinted from the Journal of College Science Teaching, college and university science professors show how they have used investigative learning--or inquiry-based instruction--to introduce students to the process of science. These first-person accounts demonstrate how students, including non-science majors, can learn to do science as it is done in the real world--through hypothesis building, observation, and experimental design. The higher education faculty represented in this book is committed to the investigative approach. As one contributor writes, "Would I return to lecturing in a traditional fashion? Not a chance. The excitement and energy of a room of students working in groups, challenging each other, and questioning each other is what I'll always want to see in my classroom."

Press, Nsta

2001-01-01

251

Effecting change in elementary school science education  

SciTech Connect

The mission of the Merck Institute for Science Education is to improve the quality of science education during the formative years of kindergarten through eighth grade. To accomplish this mission, the Institute has three primary goals: Transform the teaching of science to communicate the excitement and relevance of science; Reform the education of teachers to instill in tomorrow`s teachers an understanding and appreciation of science; and Create a consensus on the importance of elementary science education among leaders in education, business, and science. Merck has made a minimum ten year commitment of funding and resources to the Institute. The Institute will work very closely with faculty, administration, and community leaders in target school districts to enhance science education in the elementary grades of their schools. Once the Institute`s goals have been achieved in these initial partner districts, the Institute will replicate its programs in other districts.

Parravano, C.

1994-12-31

252

ALMA in Early Science (Cycles 0 and 1)  

NASA Astrophysics Data System (ADS)

ALMA's initial PI-driven science campaign ("Cycle 0") is now well underway and the deadline for the next round of Early Science ("Cycle 1") is this summer. Cycle 0 has already produced exciting results and ALMA has carried out an exciting Science Verification program. I will give an update on ALMA construction and operations and show early science highlights. I will review the capabilities available to the community in ALMA Cycle 1, which include and expanded number of antennas, increased correlator flexibility, and sensitivity to extended structure thanks to the inclusion of the ACA.

Sheth, Kartik

2012-05-01

253

Earth Sciences Environmental Earth Sciences,  

E-print Network

84 Earth Sciences­ Environmental Earth Sciences, Geology MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint Honours Degrees Sciences offers BSc Honours degrees in Geology and Environmental Earth Sciences, and your degree choice

Brierley, Andrew

254

Wine Science Wine Sciencee Science  

E-print Network

Wine Science Wine Sciencee Science Thomas Henick-Kling Professor of Enology Director of Viticulture & Enology Program #12;Wine Science Wine Science Growth of Washington Wine Industry #12;Wine Science Wine Science Wine Grapes utilized 2007 2008 2009 2010 WA 127,000 145,000 156,000 160,000 NY 24,000 26,000 30

255

Faculty of Science General Science  

E-print Network

Faculty of Science General Science The General Science program gives you maximum flexibility to explore the sciences, plus the core requirements you need for on-going, specialized studies. www.uwindsor.ca/science Rigorous, Enriching Programs The BSc General Science program is a great way to explore your many interests

256

Coulomb excitation of cadmium isotopes with protons  

Microsoft Academic Search

Low-lying positive parity levels of the isotopes in natural cadmium were Coulomb excited with 2.7-4.2 MeV protons. Eight levels of 111Cd up to 1130.4 keV and four levels of 113Cd up to 680.5 keV excitation energy, and the first 2+ states in even-even isotopes (110,112,114,116Cd) were excited. A 50 cm3 Ge(Li) detector was used to measure the deexcitation gamma-ray yields.

K. P. Singh; D. C. Tayal; Gulzar Singh; H. S. Hans

1985-01-01

257

Coulomb excitation of cadmium isotopes with protons  

Microsoft Academic Search

Low-lying positive parity levels of the isotopes in natural cadmium were Coulomb excited with 2.7--4.2 MeV protons. Eight levels of ¹¹¹Cd up to 1130.4 keV and four levels of ¹¹³Cd up to 680.5 keV excitation energy, and the first 2\\/sup +\\/ states in even-even isotopes (\\/sup 110,112,114,116\\/Cd) were excited. A 50 cm³ Ge(Li) detector was used to measure the deexcitation

K. P. Singh; D. C. Tayal; Gulzar Singh; H. S. Hans

1985-01-01

258

Collisional excitation of interstellar sulfur dioxide  

NASA Technical Reports Server (NTRS)

State-to-state rotational excitation rates for the asymmetric top molecule SO2 in collisions with low-energy He atoms have been computed. The intermolecular forces were obtained from an electron gas model, and collision dynamics were treated with the finite-order sudden approximation. The total excitation rate is probably accurate to better than 50 percent; however, individual state-to-state rates may be in error by factors of 2 or 3, and some smaller rates may be accurate only to an order of magnitude. Present results are expected to reflect within the same level of accuracy rates for excitation by collisions with H2 molecules.

Palma, Amedeo

1987-01-01

259

Setting the Scene: Basic Rules for a Safer Science Classroom  

NSDL National Science Digital Library

Six classes, six teachers--just navigating middle school is a voyage of discovery for early adolescents. We offer them a confusing array of choices, many in science. Sometimes it seems we spend too much science class time teaching organization, caution, and control. But these skills--critical to making science experiences exciting and safe--are also important science processes. This free selection includes the Table of Contents, Foreword, Introduction, and References.

Texley, Juliana; Kwan, Terry

2003-01-01

260

An Excitation-Capacitor-Optimized Dual Stator-Winding Induction Generator With the Static Excitation Controller for Wind Power Application  

Microsoft Academic Search

This paper presents an optimal scheme of excitation capacitor to decrease the capacity of static excitation controller (SEC) for dual stator-winding induction generator (DWIG) system applied in wind power generation. The investigations into reactive excitation power released by the excitation capacitor and SEC il- lustrate that the optimal excitation capacitor is not only related to generator parameters, speed range, and

Feifei Bu; Wenxin Huang; Yuwen Hu; Kai Shi

2011-01-01

261

Resonant excitation of plasma wakefield  

NASA Astrophysics Data System (ADS)

Particle accelerators are the main tool for discovering new elementary particles. Plasma based accelerator (PWFA) has been proven a very attractive new acceleration technique due to the large acceleration gradient it has reached (>50GV/m), which is two to three orders higher than the conventional radio frequency accelerators. PWFA is essentially an energy transformer transferring the energy from the drive bunches to witness bunches. For a future more compact and more affordable linear electron/positron collider, such an accelerator will require drive bunches with small longitudinal size (on the order of 100 um) and multi-kilojules of energy to access the new physics at the energy frontier. However, present relativistic electron bunch drivers carry less than 100Joules, thereby limiting the energy gain by the accelerated bunch to less than 100Joules. Proton bunches produced at CERN have been proven as potential drivers for PWFA due to the many tens of kilojules energy they carry (1e11 particles, 3.5-7TeV per particle). However, the CERN proton bunches are too long (approximately 12cm) to drive the wakefield efficiently. It has been proposed that a long particle bunch (protons, electrons, positrons, ... ) traveling in dense plasmas is subject to self-modulation instability (SMI), which transversely modulates a long bunch into multiple short bunches (on the scale of plasma wavelength) and therefore results in high acceleration amplitudes through resonant excitation. In this thesis, we demonstrate the first experimental evidence for the seeding of SMI with an electron bunch. We also use numerical simulations to study the SMI development with a higher-charge electron bunch and propose a possible experiment to demonstrate the transverse modulation directly in experiments. Moreover, we investigate with simulations the effect of transverse plasma radius on the SMI development, which is an important factor to consider when designing plasmas for future SMI and SMI-based experiments. Besides efficient drivers such as high-energy proton bunches, the PWFA also requires high transformer ratio (an indication of energy transfer efficiency) so that the witness bunch can gain energy efficiently from the drive bunch. In this thesis, we explore the possibility of reaching high transformer ratio in the weakly nonlinear PWFA regime so that the witness bunch particles can gain many times the energy of the drive bunch particles in a single acceleration stage.

Fang, Yun

262

Try Science  

NSDL National Science Digital Library

TryScience contains games and virtual reality adventures, virtual field trips to museums and science centers, and experiments. There is a Starfleet Academy virtual reality game involving communications, engineering, environments, and lifeforms; an electrolysis experiment that can be conducted online or at home; and a game about an African Naked Mole-rat colony. Experiments are categorized by: Earth science, biological science, mathematics, physical science, space science, technology and engineering, chemistry, social science, and medicine and health.

263

Students Excited by Stellar Discovery  

NASA Astrophysics Data System (ADS)

In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second -- an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU). The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. "Every day, I told myself, 'I have to find a pulsar. I better find a pulsar before this class ends,'" said Mabry. When she actually made the discovery, she could barely contain her excitement. "I started screaming and jumping up and down." Thompson was similarly expressive. "After three years of searching, I hadn't found a single thing," he said, "but when I did, I threw my hands up in the air and said, 'Yes!'." Snider said, "It actually feels really neat to be the first person to ever see something like that. It's an uplifting feeling." As part of the PSC, the students analyze real data from NRAO's Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students' teachers -- Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School -- all introduced the PSC in their classes, and interested students formed teams to continue the work. Even before the discovery, Mabry simply enjoyed the search. "It just feels like you're actually doing something," she said. "It's a good feeling." Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the follow-up observations, and Thompson joined online. "Observing with the students is very exciting. It gives the students a chance to learn about radio telescopes and pulsar observing in a very hands-on way, and it is extra fun when we find a pulsar," said Rosen. Snider, on the other hand, said, "I got very, very nervous. I expected when I went there that I would just be watching other people do things, and then I actually go to sit down at the controls. I definitely didn't want to mess something up." Everything went well, and the observations confirmed that the students had found an exotic pulsar. "I learned more in the two hours in the control room than I would have in school the whole day," Mabry said. Pulsars are spinning neutron stars that sling lighthouse beams of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its normal life. With no nuclear fuel left to produce energy to offset the stellar remnant's weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name neutron star. One tablespoon of material from a pulsar would weigh 10 million tons -- as much as a supertanker. The object that the students discovered is in a special class of pulsar that spins very fast - in this case, about 30 times per second, comparable to the speed of a kitchen blender. "The big question we need to answer first is whether this is a young pulsar or a recycled pulsar," said Maura McLaughlin, an astronomer at WVU. "A pulsar spinning that fast is very interesting as it could be newly born or it could be a very old, recycled pulsar." A recycled pulsar is one that was once in a binary system. Material from the companion star is deposited onto the pulsar, causing it to speed up, or be recycled. Mystery remains, however, about whether this pulsar has ever had a companion star. If it did, "it may be t

2011-02-01

264

Acoustics of Excited Jets: A Historical Perspective  

NASA Technical Reports Server (NTRS)

The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.

Brown, Cliffard A.

2005-01-01

265

Fear, excitement, and financial risk-taking.  

PubMed

Can fear trigger risk-taking? In this paper, we assess whether fear can be reinterpreted as a state of excitement as a result of contextual cues and promote, rather than discourage, risk-taking. In a laboratory experiment, the participants' emotional states were induced (fear vs. control), followed by a purportedly unrelated financial task. The task was framed as either a stock market investment or an exciting casino game. Our results showed that incidental fear (vs. control) induced risk-averse behaviour when the task was framed as a stock investment decision. However, fear encouraged risk-taking when the very same task was framed as an exciting casino game. The impact of fear on risk-taking was partially mediated by the excitement felt during the financial task. PMID:24661027

Lee, Chan Jean; Andrade, Eduardo B

2015-01-01

266

Mode Selective Excitation Using Coherent Control Spectroscopy  

SciTech Connect

Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, femtosecond laser pulses are spectrally broad and therefore coherently excite several molecular modes. While the temporal resolution is high, usually no mode-selective excitation is possible. This paper demonstrates the feasibility of selectively exciting specific molecular vibrations in solution phase with shaped fs laser excitation using a feedback-controlled optimization technique guided by an evolutionary algorithm. This approach is also used to obtain molecule-specific CARS spectra from a mixture of different substances. The optimized phase structures of the fs pulses are characterized to get insight into the control process. Possible applications of the spectrum control are discussed.

Singh, Ajay K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India); School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Konradi, Jakow; Materny, Arnulf [School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Sarkar, Sisir K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India)

2008-11-14

267

Faraday waves under time-reversed excitation.  

PubMed

Do parametrically driven systems distinguish periodic excitations that are time mirrors of each other? Faraday waves in a Newtonian fluid are studied under excitation with superimposed harmonic wave forms. We demonstrate that the threshold parameters for the stability of the ground state are insensitive to a time inversion of the driving function. This is a peculiarity of some dynamic systems. The Faraday system shares this property with standard electroconvection in nematic liquid crystals [J. Heuer et al., Phys. Rev. E 78, 036218 (2008)]. In general, time inversion of the excitation affects the asymptotic stability of a parametrically driven system, even when it is described by linear ordinary differential equations. Obviously, the observed symmetry has to be attributed to the particular structure of the underlying differential equation system. The pattern selection of the Faraday waves above threshold, on the other hand, discriminates between time-mirrored excitation functions. PMID:23496716

Pietschmann, Dirk; Stannarius, Ralf; Wagner, Christian; John, Thomas

2013-03-01

268

Fast pulsed excitation wiggler or undulator  

DOEpatents

A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.

van Steenbergen, Arie (Shoreham, NY)

1990-01-01

269

Search for excited leptons at LEP  

Microsoft Academic Search

Excited leptons have been searched for using data recorded by the OPAL detector at LEP. No evidence for such particles has been found. From the study of e+e- --> l+l-gammagamma events, lower limits on the masses of spin-1\\/2 excited leptons are found to be 44.9 GeV at 95% confidence level. From the study of e+e- -->l+l-gamma events, upper limits on

M. Z. Akrawy; Gideon Alexander; J. Allison; P. P. Allport; K. J. Anderson; J. C. Armitage; Geoffrey T J Arnison; P. Ashton; Georges Azuelos; J. T. M. Baines; A. H. Ball; J. Banks; G. J. Barker; R. J. Barlow; J Richard Batley; J. Becker; T. Behnke; K. W. Bell; G. Bella; Siegfried Bethke; O. Biebel; U. Binder; Ian J Bloodworth; P. Bock; Horst Breuker; R. M. Brown; R. Brun; A. Buijs; Helfried J Burckhart; P. Capiluppi; R. K. Carnegie; A. A. Carter; J. R. Carter; C. Y. Chang; D. G. Charlton; J. T. M. Chrin; I. Cohen; W. J. Collins; J. E. Conboy; M. Couch; M. Coupland; M. Cuffiani; S. Dado; G. M. Dallavalle; P. Debu; M. M. Deninno; A. Dieckmann; Michael Dittmar; M. S. Dixit; E. Duchovni; I. P. Duerdoth; D J P Dumas; H. El Mamouni; P. A. Elcombe; P. G. Estabrooks; E. Etzion; Franco Luigi Fabbri; Philippe Farthouat; H. M. Fischer; D. G. Fong; M. T. French; C. Fukunaga; A. Gaidot; O. Ganel; J. W. Gary; J. Gascon; N. I. Geddes; C. N. P. Gee; C. Geich-Gimbel; S. W. Gensler; F. X. Gentit; G. Giacomelli; V. Gibson; W. R. Gibson; James D Gillies; J. Goldberg; M. J. Goodrick; W. Gorn; D. Granite; E. Gross; P. Grosse-Wiesmann; Jacob Grunhaus; H. Hagedorn; J. Hagemann; M. Hansroul; C. K. Hargrove; J. Hart; P. M. Hattersley; M. Hauschild; C. M. Hawkes; E. Heflin; Richard J Hemingway; R. D. Heuer; J. C. Hill; S. J. Hillier; C. Ho; J. D. Hobbs; P. R. Hobson; D. Hochman; B. Holl; R James Homer; S. R. Hou; C. P. Howarth; R. E. Hughes-Jones; P. Igo-Kemenes; H. Ihssen; D. C. Imrie; A. Jawahery; P. W. Jeffreys; H. Jeremie; Martin Paul Jimack; M. Jobes; R. W. L. Jones; P. Jovanovic; D A Karlen; K. Kawagoe; T. Kawamoto; R. G. Kellogg; B. W. Kennedy; C. Kleinwort; D. E. Klem; G. Knop; T. Kobayashi; T. P. Kokott; L. Köpke; R V Kowalewski; H. Kreutzmann; J. von Krogh; J. Kroll; M. Kuwano; P. Kyberd; G. D. Lafferty; F. Lamarche; W. J. Larson; J. G. Layter; P. Le Du; P. Leblanc; A. M. Lee; Daniel Lellouch; P. Lennert; L. Lessard; L. Levinson; S. L. Lloyd; F. K. Loebinger; J. M. Lorah; B. Lorazo; Michael J Losty; J. Ludwig; N. Lupu; J. Ma; A. A. MacBeth; M. Mannelli; S. Marcellini; G. Maringer; A. J. Martin; J. P. Martin; T. Mashimo; P. Mättig; U. Maur; T. J. McMahon; A. C. McPherson; F. Meijers; D. Menszner; F. S. Merritt; H. Mes; Aldo Michelini; R. P. Middleton; G. Mikenberg; D. J. Miller; C. Milstene; M. Minowa; W. Mohr; A. Montanari; T. Mori; M. W. Moss; P. G. Murphy; W. J. Murray; B. Nellen; H. H. Nguyen; M. Nozaki; A. J. P. O'Dowd; S. W. O'Neale; B. P. O'Neill; F. G. Oakham; F. Odorici; M. Ogg; H. Oh; M. J. Oreglia; S. Orito; J. P. Pansart; G. N. Patrick; S. J. Pawley; P. Pfister; J. E. Pilcher; James L Pinfold; D. E. Plane; B. Poli; A. Pouladdej; T. W. Pritchard; G. Quast; J. Raab; M. W. Redmond; D. L. Rees; M. Regimbald; K. Riles; C. M. Roach; S. A. Robins; A. Rollnik; J. M. Roney; S. Rossberg; A. M. Rossi; P. Routenburg; K. Runge; O. Runolfsson; S. Sanghera; R. A. Sansum; M. Sasaki; B. J. Saunders; A. D. Schaile; W. Schappert; P. Scharff-Hansen; H. von der Schmitt; S. Schreiber; J. Schwarz; A. Shapira; B. C. Shen; P. Sherwood; A. Simon; P. Singh; G. P. Siroli; A M Smith; A. M. Smith; T. J. Smith; G. A. Snow; E. J. Spreadbury; R. W. Springer; M. Sproston; K. Stephens; H. E. Stier; R. Ströhmer; D. Strom; H. Takeda; T. Takeshita; T. Tsukamoto; M. F. Turner; G. Tysarczyk-Niemeyer; D. van den Plas; G. J. Vandalen; G. Vasseur; C. J. Virtue; A. Wagner; C. Wahl; C. P. Ward; D. R. Ward; J. Waterhouse; P. M. Watkins; A. T. Watson; N. K. Watson; M. Weber; S. Weisz; N. Wermes; M. Weymann; G. W. Wilson; J. A. Wilson; I Wingerter-Seez; V.-H. Winterer; N. C. Wood; S A Wotton; B. Wuensch; T. R. Wyatt; R. Yaari; Y. Yang; G. Yekutieli; T. Yoshida; W. Zeuner; G. T. Zorn

1990-01-01

270

Critical fronts in initiation of excitation waves  

NASA Astrophysics Data System (ADS)

We consider the problem of initiation of propagating waves in a one-dimensional excitable fiber. In the FitzHugh-Nagumo theory, the key role is played by “critical nucleus” and “critical pulse” solutions whose (center-) stable manifold is the threshold surface separating initial conditions leading to propagation and those leading to decay. We present evidence that in cardiac excitation models, this role is played by “critical front” solutions.

Idris, I.; Biktashev, V. N.

2007-08-01

271

Intrinsic asymmetry of polar motion excitation  

NASA Astrophysics Data System (ADS)

Anisotropy of the pole tide and Earth triaxiality make the polar motion excitation asymmetric with respect to and y pole coordinates (Okamoto and Sasao 1977). After having proposed a general description of these non isotropic effects, we show that there are significant in light of the contemporaneous accuracy of the pole coordinates and cannot be cast aside in the interpretation of the Chandler wobble excitation

Bizouard, C.

2012-12-01

272

Magnesium induces neuronal apoptosis by suppressing excitability  

Microsoft Academic Search

In clinical obstetrics, magnesium sulfate (MgSO4) use is widespread, but effects on brain development are unknown. Many agents that depress neuronal excitability increase developmental neuroapoptosis. In this study, we used dissociated cultures of rodent hippocampus to examine the effects of Mg++ on excitability and survival. Mg++-induced caspase-3-associated cell loss at clinically relevant concentrations. Whole-cell patch-clamp techniques measured Mg++ effects on

W H Dribben; L N Eisenman; S Mennerick

2010-01-01

273

Electron-impact vibrational excitation of tetrahydrofuran  

NASA Astrophysics Data System (ADS)

Low-energy differential and integral cross sections for the electron-impact vibrational excitation of tetrahydrofuran are presented. The data concern four features in the vibrational excitation electron energy-loss spectrum of tetrahydrofuran over the energy-loss range of 0-0.9 eV. The results show weak influence from long-range dipole interactions, being mainly isotropic. Comparison with earlier work is presented.

Khakoo, M. A.; Orton, D.; Hargreaves, L. R.; Meyer, N.

2013-07-01

274

Vibrationally Excited Molecular Hydrogen Near Herschel 36  

E-print Network

We present the first high resolution UV spectra toward Herschel 36, a Trapezium-like system of high-mass stars contained within the Lagoon Nebula (M8, NGC 6523). The spectra reveal extreme ro-vibrational excitation of molecular hydrogen in material at a single velocity or very small range of velocities, with this component presumably lying near the star system and undergoing fluorescent excitation. The overall H$_2$ excitation is similar to, but apparently larger than, that seen towards HD 37903 which previously showed the largest vibrationally excited H$_2$ column densities seen in UV absorption spectra. While the velocities of the highly excited H$_2$ lines are consistent within each observation, it appears that they underwent a $\\sim$60 km s$^{-1}$ redshift during the 3.6 years between observations. In neither case does the velocity of the highly excited material match the velocity of the bulk of the line-of-sight material which appears to mostly be in the foreground of M8. Recent work shows unusually exci...

Rachford, Brian L; Ross, Teresa L

2014-01-01

275

Excited state dynamics of phthalocyanine films  

SciTech Connect

Femtosecond pump-probe transient absorption measurements were performed for thermally evaporated polycrystalline vanadyl and lead phthalocyanine (VOPc and PbPc) films in order to obtain information about the excitation energy migration and relaxation. The films were shown to be composed of phase II and amorphous material. Fast excitation localization in phase II was concluded from measurement and analysis of the ground and excited state spectra. Comparison of the ground state, difference absorption, and luminescence spectra suggests a small oscillator strength of the electronic transition from the lowest excited state to the ground state. The influence of local heating on the transient spectra is discussed, and the possibility to obtain the excitation decay kinetics free from this influence is proposed. Exciton-exciton annihilation with a time dependent rate (proportional to t{sup -0.5}) is observed in both films. This is explained by one-dimensional diffusion-limited annihilation. Linear relaxation times are equal to 28{+-}6 and 42{+-}8 ps and approximate intermolecular excitation hopping times of 0.1 divide 0.4 and 0.02 divide 0.08 ps were determined for VOPc and PbPc, respectively. 22 refs., 8 figs., 1 tab.

Gulbians, V.; Valkunas, L. [Vilnius Inst. of Physics (Lithuania)] [Vilnius Inst. of Physics (Lithuania); Chachisvillis, M.; Sundstrom, V. [Lund Univ. (Sweden)] [Lund Univ. (Sweden)

1996-02-08

276

Exciting threshold dependence of self-sustained spikes in excitable neurons  

NASA Astrophysics Data System (ADS)

The dependence of self-sustained spikes on the exciting threshold is investigated by two neuron models with an initial stimulus. We find that in the sub-excitable regime of neuron, the exciting threshold is the key factor for an initial stimulus to induce self-sustained spikes, which is robust to the network structures. Furthermore, we even observe self-sustained spikes in a one-dimensional chain, in contrast to previous results stating that an external pacing or a loop structure is the necessary condition to sustain spikes. While in the excitable regime of neuron, we also find the effect of the exciting threshold, i.e. that the lower exciting threshold will result in strong firing synchronization but the higher threshold will result in weak firing synchronization. These findings may be helpful in understanding the microscopic mechanism of epileptic seizures.

Wang, Jianxiong; Liu, Zonghua

2011-07-01

277

Computer Science  

NSDL National Science Digital Library

Computer science is the study of computational systems and their use in representing important problems in science and society. Major topics include computational science, software systems, network systems, theory of computation, machine learning, and human-computer interaction.

K-12 Outreach,

278

Earth Sciences Environmental Earth Sciences,  

E-print Network

94 Earth Sciences­ Environmental Earth Sciences, Geology Degree options MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint placement. * The Geology and Environmental Earth Sciences degrees are accredited by the Geological Society

Brierley, Andrew

279

Van der Waals interaction of excited media  

E-print Network

Casimir interaction between two media of ground-state atoms is well described with the help of Lifshitz formula depending upon permittivity of media. We will show that this formula is in contradiction with experimental evidence for excited atoms. We calculate Casimir force between two atoms if one of them or both atoms are excited. We use methods of quantum electrodynamics specially derived for the problem. It enables us to take into account excited-state radiation widths of atoms. Then we calculate the force between excited atom and medium of ground-state atoms. The results are in agreement with the ones, obtained by other authors using perturbation theory or linear response theory. Generalization of our results to the case of interaction between two media of excited atoms results in a formula, which is in not only in quantitative, but in qualitative contradiction with Lifshits formula. This contradiction disappears if media of ground-state atoms are taken. Moreover, our result does not include permittivity of the media. It includes the quantity which differs from the permittivity only for excited atoms. The main features of our results are as follows. The interaction is resonant; the force may be either attractive or repulsive depending on resonant frequencies of the atoms of different media; the value of Casimir force may be several orders of magnitude lager than that predicted by Lifshitz formula. The features mentioned here are in agreement with known experimental and theoretical evidences obtained by many authors for interaction of a single excited atom with dielectric media.

Yury B. Sherkunov

2005-03-05

280

Electronic excitations in long polyenes revisited.  

PubMed

We apply the valence shell model OM2 [W. Weber and W. Thiel, Theor. Chem. Acc. 103, 495, (2000)] combined with multireference configuration interaction (MRCI) to compute the vertical excitation energies and transition dipole moments of the low-energy singlet excitations in the polyenes with 4 ? N ? 22?-electrons. We find that the OM2/MRCI descriptions closely resemble those of Pariser-Parr-Pople (PPP) ?-electron models [P. Tavan and K. Schulten, Phys. Rev. B 36, 4337, (1987)], if equivalent MRCI procedures and regularly alternating model geometries are used. OM2/MRCI optimized geometries are shown to entail improved descriptions particularly for smaller polyenes (N ? 12), for which sizeable deviations from the regular model geometries are found. With configuration interaction active spaces covering also the ?- in addition to the ?-electrons, OM2/MRCI excitation energies turn out to become smaller by at most 0.35 eV for the ionic and 0.15 eV for the covalent excitations. The particle-hole (ph) symmetry, which in Pariser-Parr-Pople models arises from the zero-differential overlap approximation, is demonstrated to be only weakly broken in OM2 such that the oscillator strengths of the covalent 1B(u)(-) states, which artificially vanish in ph-symmetric models, are predicted to be very small. According to OM2/MRCI and experimental data the 1B(u)(-) state is the third excited singlet state for N < 12 and becomes the second for N ? 14. By comparisons with results of other theoretical approaches and experimental evidence we argue that deficiencies of the particular MRCI method employed by us, which show up in a poor size consistency of the covalent excitations for N > 12, are caused by its restriction to at most doubly excited references. PMID:22462859

Schmidt, Maximilian; Tavan, Paul

2012-03-28

281

Electronic excitations in long polyenes revisited  

NASA Astrophysics Data System (ADS)

We apply the valence shell model OM2 [W. Weber and W. Thiel, Theor. Chem. Acc. 103, 495, (2000)] combined with multireference configuration interaction (MRCI) to compute the vertical excitation energies and transition dipole moments of the low-energy singlet excitations in the polyenes with 4 <= N <= 22?-electrons. We find that the OM2/MRCI descriptions closely resemble those of Pariser-Parr-Pople (PPP) ?-electron models [P. Tavan and K. Schulten, Phys. Rev. B 36, 4337, (1987)], if equivalent MRCI procedures and regularly alternating model geometries are used. OM2/MRCI optimized geometries are shown to entail improved descriptions particularly for smaller polyenes (N <= 12), for which sizeable deviations from the regular model geometries are found. With configuration interaction active spaces covering also the ?- in addition to the ?-electrons, OM2/MRCI excitation energies turn out to become smaller by at most 0.35 eV for the ionic and 0.15 eV for the covalent excitations. The particle-hole (ph) symmetry, which in Pariser-Parr-Pople models arises from the zero-differential overlap approximation, is demonstrated to be only weakly broken in OM2 such that the oscillator strengths of the covalent 1Bu- states, which artificially vanish in ph-symmetric models, are predicted to be very small. According to OM2/MRCI and experimental data the 1Bu- state is the third excited singlet state for N < 12 and becomes the second for N >= 14. By comparisons with results of other theoretical approaches and experimental evidence we argue that deficiencies of the particular MRCI method employed by us, which show up in a poor size consistency of the covalent excitations for N > 12, are caused by its restriction to at most doubly excited references.

Schmidt, Maximilian; Tavan, Paul

2012-03-01

282

Lessons Learned from Conducting a K-12 Project to Revitalize Achievement by Using Instrumentation in Science Education  

ERIC Educational Resources Information Center

A student's first introduction to engineering and technology is typically through high school science labs. Unfortunately, in many high schools, science labs often make use of antiquated tools that fail to deliver exciting lab content. As a result, many students are turned off by science, fail to excel on standardized science exams, and do…

Kapila, Vikram; Iskander, Magued

2014-01-01

283

U of M students and staff share the excitement of STEM subjects with middle and high school students  

E-print Network

U of M students and staff share the excitement of STEM subjects with middle and high school team was able to introduce science and engineering concepts and projects to Circle of Life high school, and let the high school students explore. This year's projects included making Silly Putty, crystals, ice

Amin, S. Massoud

284

AN EXCITING OPPORTUNITY TO EXPERIENCE UNCOMMON LEARNING The Department of Cell Biology and Neuroscience at Montana State University offers an  

E-print Network

or entry into medical, dental, other health professions and graduate school. All of our students have in medicine or other health professions, or are interested in a biomedical sciences career in researchAN EXCITING OPPORTUNITY TO EXPERIENCE UNCOMMON LEARNING The Department of Cell Biology

Maxwell, Bruce D.

285

Crop Science Investigation (CSI) Network  

NSDL National Science Digital Library

Crop Science Investigation (CSI) Network        This site is designed to serve as a clearinghouse of lesson plans and other materials useful for teaching 4-H and FFA youth about crop and soil sciences.  Check out this site for information to use in your classroom, workshops, or 4-H meetings.       As youth become less connected with agriculture, it is essential to teach them about agriculture. A series of workshops, called Crop Science Investigation or CSI was created to help spark the interest of youth to learn about crops and plants.Dig into some interesting facts about Nebraska crops.Learn how crops grow and factors that affect them.Learn about exciting career opportunities related to crop and plant science. The University of Nebraska offers great majors for anyone interested in anything plants!  Check it out!

286

Astronomical Approach to Physical Science Curriculum  

NASA Astrophysics Data System (ADS)

The Astronomical Approach to Physical Science Curriculum (AAPS Curriculum) is an innovative curriculum that incorporates an astronomy theme into an inquiry-based physical science curriculum for pre-service, elementary school teachers. Many physical science courses are a non-cohesive collection of topics required for the state teaching license. Through the use of astronomy and space science examples, the AAPS Curriculum will have a coherent theme that ties the wide variety of physical science topics together and provides many real world applications for the topics covered in the course. This new curriculum will incorporate the applications of knowledge to complete the learning cycle-exploration, concept introduction, application. Astronomy and space science applications will be emphasized throughout the curriculum. The theme of astronomy was chosen to prepare elementary school teachers for teaching astronomy and space science in their classroom, as this is a topic in which many school children are consistently interested. Since astronomy is a topic that can be used as a springboard to teach many other areas of study, we want teachers who are knowledgeable in topics of astronomy so they are capable of preparing creative lessons throughout their entire curriculum that are exciting to their students. The AAPS Curriculum will train college students to become teachers who are comfortable with physical science and astronomy topics and who are excited to teach these topics in their classroom. Funding for this work is provided by the IDEAS grant program of the Space Telescope Science Institute.

Manning, H. L. K.; Churukian, A. D.

2004-11-01

287

Tone-excited jet: Theory and experiments  

NASA Technical Reports Server (NTRS)

A detailed study to understand the phenomenon of broadband jet-noise amplification produced by upstream discrete-tone sound excitation has been carried out. This has been achieved by simultaneous acquisition of the acoustic, mean velocity, turbulence intensities, and instability-wave pressure data. A 5.08 cm diameter jet has been tested for this purpose under static and also flight-simulation conditions. An open-jet wind tunnel has been used to simulate the flight effects. Limited data on heated jets have also been obtained. To improve the physical understanding of the flow modifications brought about by the upstream discrete-tone excitation, ensemble-averaged schlieren photographs of the jets have also been taken. Parallel to the experimental study, a mathematical model of the processes that lead to broadband-noise amplification by upstream tones has been developed. Excitation of large-scale turbulence by upstream tones is first calculated. A model to predict the changes in small-scale turbulence is then developed. By numerically integrating the resultant set of equations, the enhanced small-scale turbulence distribution in a jet under various excitation conditions is obtained. The resulting changes in small-scale turbulence have been attributed to broadband amplification of jet noise. Excellent agreement has been found between the theory and the experiments. It has also shown that the relative velocity effects are the same for the excited and the unexcited jets.

Ahuja, K. K.; Lepicovsky, J.; Tam, C. K. W.; Morris, P. J.; Burrin, R. H.

1982-01-01

288

Vibrationally Excited Molecular Hydrogen Near Herschel 36  

NASA Astrophysics Data System (ADS)

We present the first high resolution UV spectra toward Herschel 36, a Trapezium-like system of high-mass stars contained within the Lagoon Nebula (M8, NGC 6523). The spectra reveal extreme ro-vibrational excitation of molecular hydrogen in material at a single velocity or very small range of velocities, most likely the largest ever seen in UV absorption spectra. While the velocities of the highly excited H2 lines are consistent within each observation, it appears that they underwent a ?60 km s-1 redshift during the 3.6 years between observations. In neither case does the velocity of the highly excited material match the velocity of the bulk of the line-of-sight material which appears to mostly be in the foreground of M8. Recent work shows unusually excited CH and CH+ lines and several unusually broad Diffuse Interstellar Bands (DIBs) towards Herschel 36. Along with the H2 excitation, all of these findings appear to be related to the extreme environment within ˜0.1 pc of the massive young stellar system.

Rachford, Brian L.; Snow, T. P.; Ross, T.

2014-01-01

289

Targeting individual excited states in DMRG.  

NASA Astrophysics Data System (ADS)

The low-lying excited states of ?-conjugated molecules are important for the development of novel devices such as lasers, light-emitting diodes, photovoltaic cells, and field-effect transistors [1,2]. The ab-intio Density Matrix Renormalization Group (DMRG) provides a powerful way to explore the electronic structure of quasi-one-dimensional systems such as conjugated organic oligomers. However, DMRG is limited to targeting only low-lying excited states through state-averaged DMRG (SDMRG). There are several drawbacks; state-averaging degrades the accuracy of the excited states and is limited to at most a few of the low-lying states [3]. In this study, we present a new method for targeting higher individual excited states. Due to progress in the field of numerical analysis presented by Van Der Horst and others [4], we are able to target individual excited states of the Hamiltonian. This is accomplished by modifying the Jacobi-Davidson algorithm via a ``Harmonic Ritz'' procedure. We will present studies of oligoacenes and polyenes that compare the accuracy of SDMRG and Harmonic Davidson DMRG. [1] Burroughes, et al. , Nature 347, 539 (1990). [2] Shirota, J. Mater. Chem. 10, 1, (2000). [3] Ramasesha, Pati, Krishnamurthy, Shuai, Bredas, Phys. Rev. B. 54, 7598, (1997). [4] Bai, Demmel, Dongarra, Ruhe, Van Der Horst, Templates for the Solution of Algebraic Eigenvalue Problems, SIAM, 2000.

Dorando, Jonathan; Hachmann, Johannes; Kin-Lic Chan, Garnet

2007-03-01

290

Visionlearning: The Process of Science  

NSDL National Science Digital Library

This classroom-tested instructional unit was developed to build interest and excitement about the practice of science by real people in real laboratories. It takes learners on a journey to understand how a good experiment is designed, how to recognize bias and error, how to perform an investigation into the natural world, and how to clearly communicate about the findings. It is divided into 15 sections, many of which can be parsed out separately. Topics include scientific ethics, funding for science, research methods, data analysis/interpretation, statistics, error and uncertainty, the peer review process, and understanding scientific articles.

2010-09-30

291

FOREWORD Nanomaterials science Nanomaterials science  

NASA Astrophysics Data System (ADS)

The nanometer regime covers the transition from condensed matter behavior to atomic and molecular properties and thus is a very rich but also very demanding area in materials science. Close to the condensed matter side, properties and functions might still very well be scalable, whereas close to the atomic and molecular side, the scalability is mostly lost. Properties and functions change qualitatively or quantitatively by orders of magnitude when the dimensions become smaller than a critical size in the nanometer range. Examples are the ballistic regime for electron or spin transport at dimensions below the mean free path, near-field effects in scanning near-field optical microscopy and quantum wells when the dimensions are below an appropriate wavelength, novel electronic, mechanical, and chemical properties when the number of bulk atoms becomes smaller than that of surface atoms, quantum conduction, and Coulomb blockade. Thus, by going below a certain size, an abundance of novel properties and functions are at one's disposal, or, in other words, we can functionalize materials simply by reducing their size to the nanoscale. The key to the future lies in the functions that we give to materials, not just in finding 'novel functional materials'. This catch expression in many materials science programs and initiatives of the past two decades sounds great, but it is not what really counts. All materials are functional in one way or another and, therefore, all new materials are 'novel functional materials'. Certainly, finding new materials is always an important part of progress, but we should also focus on the much larger domain of novel functions that we can give to existing or modified materials. A good example is semiconductors: they are fifty or more years old and their properties are very well known, but they were not of widespread interest and use until the transistor changed their destiny into being the central material in the information technology revolution. Interfaces gave them their functions, and shaping them into ever-smaller functional components made them indispensably omnipresent as transistors—produced in billions per person and per year—and they are no doubt the rulers of today's technical world. The semiconductor and transistor serve as an inspiring example of functionalizing materials. The developments of microelectronics profited very much from scalability, that is, the properties and functions do not change significantly with size. Therefore, every step toward smaller dimensions was a technical and commercial challenge with risks well under control. The transition to the nanoscale, however, is discontinuous. Examples of this transition are the local probe methods that exploit the mechanically controlled proximity to the object under consideration and that have become indispensable as microscopes and as measuring and modifying tools, the size of molecular components that are much smaller than the smallest possibly achievable transistor, the properties and functions of materials below a critical size as mentioned above, the continuum properties versus discrete ones, and novel concepts inspired by living nature. Those novel concepts include growing circuits first and building the active components at the nodes afterwards and measuring weak by weak, small by small, and many by many. It is these discontinuous steps that make the nanoscale different, not just smaller. They pose exciting challenges, open great opportunities and nearly unlimited possibilities, but they also carry serious technical, commercial, environmental, and health risks. The nanoscale is also a great opportunity for materials science in general. Materials science is interdisciplinary per se. A materials scientist should have a reasonable understanding of physics, chemistry, engineering, and more recently, also biology. Certainly one can always team up with representatives from other disciplines and forge collaborations. However, an effective team can only emerge from a common understanding of the respective languages and problems. Th

Rohrer, Heinrich

2010-10-01

292

Coordination of under excitation limiters and loss of excitation relays with generator capability  

Microsoft Academic Search

This paper presents a brief review of the coordination issues between under excitation limiters (UELs), loss of excitation relays (LOEs) and generator capability. The generator's capability limitations in the leading power factor region are discussed. Present industry practice and some common alternatives of LOE settings are reviewed. The settings of the UEL are reviewed in this context.

G. Roger Bérubé; Les M. Hajagos

2009-01-01

293

Patterns of conductivity in excitable automata with updatable intervals of excitations  

NASA Astrophysics Data System (ADS)

We define a cellular automaton where a resting cell excites if number of its excited neighbors belong to some specified interval and boundaries of the interval change depending on ratio of excited and refractory neighbors in the cell's neighborhood. We calculate excitability of a cell as a number of possible neighborhood configurations that excite the resting cell. We call cells with maximal values of excitability conductive. In exhaustive search of functions of excitation interval updates we select functions which lead to formation of connected configurations of conductive cells. The functions discovered are used to design conductive, wirelike, pathways in initially nonconductive arrays of cells. We demonstrate that by positioning seeds of growing conductive pathways it is possible to implement a wide range of routing operations, including reflection of wires, stopping wires, formation of conductive bridges, and generation of new wires in the result of collision. The findings presented may be applied in designing conductive circuits in excitable nonlinear media, reaction-diffusion chemical systems, neural tissue, and assemblies of conductive polymers.

Adamatzky, Andrew

2012-11-01

294

Earth Sciences Division annual report 1989  

SciTech Connect

This Annual Report presents summaries of selected representative research activities from Lawrence Berkeley Laboratory grouped according to the principal disciplines of the Earth Sciences Division: Reservoir Engineering and Hydrology, Geology and Geochemistry, and Geophysics and Geomechanics. We are proud to be able to bring you this report, which we hope will convey not only a description of the Division's scientific activities but also a sense of the enthusiasm and excitement present today in the Earth Sciences.

Not Available

1990-06-01

295

Science Signaling Podcast: 06 May 2008  

NSDL National Science Digital Library

This conversation is about research highlighted in Editors' Choice titled, "What’s So Exciting About Glia?" The highlighted article is R. Káradóttir, N. B. Hamilton, Y. Bakiri, D. Attwell, Spiking and nonspiking classes of oligodendrocyte precursor glia in CNS white matter. Nat. Neurosci. 11, 450–456 (2008). (Length: 6 min; file size: 2.61 MB; file format: mp3; location: http://podcasts.aaas.org/science_signaling/ScienceSignaling_080506.mp3)

Elizabeth M. Adler (American Association for the Advancement of Science;Science Signaling REV); Annalisa M. VanHook (American Association for the Advancement of Science;Science Signaling REV)

2008-05-06

296

Some Aspects of the Current Revolution in the Earth Sciences  

ERIC Educational Resources Information Center

Summarizes the present state of sea-floor spreading theory, elaborates upon some apparent consequences,and makes some suggestions about future education in the earth sciences. The author concludes that the future of the earth sciences looks bright and exciting. (RR)

Wilson, J. Tuzo

1969-01-01

297

Adventures in Rocket Science. EG-2007-12-179-MSFC  

ERIC Educational Resources Information Center

This guide was prepared as a tool useful for informal education venues (4-H, Boys and Girls Clubs, Boy Scouts, Girl Scouts, etc.), science clubs and related programs, and can be adopted for formal education settings. An exciting and productive study in rocket science can be implemented using the selected activities for the above-mentioned…

Huegele, Vince; Hill, Kristy; Terry, Brenda

2008-01-01

298

"Celebrate Science" Has Formula for Hands-On Learning  

ERIC Educational Resources Information Center

Cost-effective, easily replicated program is a win-win situation for high schoolers who teach science and for their elementary students. The thank-you letter from Leslie, a grade-schooler in San Diego County's Ramona Unified School District, speaks volumes about the excitement generated by "Celebrate Science"--an innovative, standards-based…

Brydolf, Carol

2012-01-01

299

A nontraditional computer graphics course for computer science students  

Microsoft Academic Search

The recent theoretical and technological advancement in computer graphics has brought not only exciting changes to the computing field but also new challenges to computer science educators. One of the challenges is effective teaching of computer graphics to computer science students. Several speakers at the SIGGRAPH \\

Zhigalzg Xiang

1994-01-01

300

Excited states in electronic structure calculations  

NASA Astrophysics Data System (ADS)

A first-principles quasiparticle approach to the electronic excitation energies in crystals and at surfaces is described. The quasiparticle energies are calculated within the GW approximation for comparison with photoemission and other spectroscopic experiments. Applications of the method to bulk semiconductors and the Si(111)2x1, Ge(111)2x1, and H/Si(111) surfaces are presented. In both cases, significant self-energy corrections arising from many-electron effects to the excitation energies are found. Using atomic positions from total energy minimization, the calculated excitation energies explain quantitatively the experimental spectra. This approach provides an ab initio means for analyzing and predicting results from spectroscopic probes.

Louie, S. G.

1992-07-01

301

Self excitation of iron core homopolar generators  

NASA Astrophysics Data System (ADS)

In the interest of reducing homopolar generator (HPG) auxiliary requirements, a self-excited field coil for pulsed duty, iron-core HPG has been developed and tested at the Center for Electromechanics at the University of Texas. In order to minimize rotor energy expended during excitation, a low-resistance, low-inductance coil was desired to allow field current to rise as rapidly as possible. A seven-turn field coil, having a nominal resistance of 500 micro-ohms was fabricated for the compact HPG system tester and subsequently tested. At 6,000 rpm, a field current rise time of 1 sec was achieved and resulted in an average peak field density of 1.94 T. Only 300 kJ, about 13 percent of the 2.27 MJ stored in the rotor was required to fully excite the generator.

Perkins, D. E.; Nalty, K. E.; Walls, W. A.

1986-11-01

302

'Safe' Coulomb Excitation of {sup 30}Mg  

SciTech Connect

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient {gamma} spectrometer MINIBALL. Using {sup 30}Mg ions accelerated to an energy of 2.25 MeV/u together with a thin {sup nat}Ni target, Coulomb excitation of the first excited 2{sup +} states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation {gamma}-ray yields the B(E2;0{sub gs}{sup +}{yields}2{sub 1}{sup +}) value of {sup 30}Mg was determined to be 241(31)e{sup 2} fm{sup 4}. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope {sup 30}Mg resides outside the 'island of inversion'.

Niedermaier, O.; Scheit, H.; Bildstein, V.; Boie, H.; Fitting, J.; Hahn, R. von; Koeck, F.; Lauer, M.; Pal, U.K.; Podlech, H.; Repnow, R.; Schwalm, D. [Max-Planck-Insitut fuer Kernphysik, Heidelberg (Germany); Alvarez, C.; Ames, F.; Bollen, G.; Emhofer, S.; Habs, D.; Kester, O.; Lutter, R.; Rudolph, K. [Ludwig-Maximilians-Universitaet, Munich (Germany)] [and others

2005-05-06

303

NMR solvent peak suppression by nonlinear excitation  

NASA Astrophysics Data System (ADS)

Most existing NMR solvent peak suppression sequences provide a satisfactory dependence of the intensity of excited signals on frequency but poor phase characteristics. In practice this leads to spectral distortions which generally become more severe as the frequency selectivity of the sequence is increased. However, it is shown that by working well outside the linear response regime, excitation schemes which combine high frequency selectivity with good phase properties may be devised. Sequences of six rectangular radio-frequency pulses were discovered using a combination of coherent averaging theory to treat the near-resonant behavior and numerical simulation further from resonance. Extensive use of symmetry greatly simplifies both the coherent averaging calculations and the numerical simulations. The new pulse sequences have been given the acronym NERO (nonlinear excitation rejecting on-resonance). Experimental spectra of an enzyme in dilute aqueous solution are shown.

Levitt, Malcolm H.

1988-03-01

304

Two photon excited fluorescence from diamond nanoparticles  

NASA Astrophysics Data System (ADS)

The possibility of two photon eaxcited fluorescence by diamond nanoparticles is an interesting nonlinear phenomenon. We have grown 20-100 nm diamond nanoparticles by using chemical vapor deposition (CVD) and characterized their properties by using complementary techniques of AFM, SEM, and Raman spectroscopy.footnotetextR. Chakraborty, S. C. Sharma, and J. K. LaRoque, J. Nano Research, 12, 1123 (2010)^,footnotetextR. Chakraborty and S. C. Sharma, Physica B, 406, 4170 (2011) In this work, we have utilized femtosecond laser based two-photon excitation to study the emission of visible light (˜ 530 nm) as functions of the excitation wavelength (750-850 nm), excitation power, and size of the NPs. These results and their potential applications will be discussed.

Singh, Ankit; Ajaeroh, Mathias; Mohanty, Samar; Sharma, Suresh

2012-10-01

305

Drift-induced excitable localized states.  

PubMed

Excitable localized states, spatial structures which possess both the features of temporal excitable pulses and of transverse cavity solitons, have been theoretically predicted in model systems as single pulses of light localized in space with a finite and deterministic duration. We study experimentally the nucleation of laser localized structures on a device defect and its motion along a spatial gradient. We demonstrate that in the reference frame of the drifting localized structure, the resulting dynamics presents the typical features of excitable systems. In particular, for specific parameter values, we observe that the nucleation of laser localized structures is triggered by noise, while the drift of the localized structure up to a spatial region where it vanishes provides the deterministic orbit which brings the system back to its initial rest state. The control of such structures may open the way to novel applications of localized structures beyond that of simple stationary bits. PMID:24476270

Turconi, M; Giudici, M; Barland, S

2013-12-01

306

"Safe" Coulomb excitation of 30Mg.  

PubMed

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion." PMID:15904283

Niedermaier, O; Scheit, H; Bildstein, V; Boie, H; Fitting, J; von Hahn, R; Köck, F; Lauer, M; Pal, U K; Podlech, H; Repnow, R; Schwalm, D; Alvarez, C; Ames, F; Bollen, G; Emhofer, S; Habs, D; Kester, O; Lutter, R; Rudolph, K; Pasini, M; Thirolf, P G; Wolf, B H; Eberth, J; Gersch, G; Hess, H; Reiter, P; Thelen, O; Warr, N; Weisshaar, D; Aksouh, F; Van den Bergh, P; Van Duppen, P; Huyse, M; Ivanov, O; Mayet, P; Van de Walle, J; Aystö, J; Butler, P A; Cederkäll, J; Delahaye, P; Fynbo, H O U; Fraile, L M; Forstner, O; Franchoo, S; Köster, U; Nilsson, T; Oinonen, M; Sieber, T; Wenander, F; Pantea, M; Richter, A; Schrieder, G; Simon, H; Behrens, T; Gernhäuser, R; Kröll, T; Krücken, R; Münch, M; Davinson, T; Gerl, J; Huber, G; Hurst, A; Iwanicki, J; Jonson, B; Lieb, P; Liljeby, L; Schempp, A; Scherillo, A; Schmidt, P; Walter, G

2005-05-01

307

LMM Auger primary excitation spectra of copper  

NASA Astrophysics Data System (ADS)

The shape and intensity of measured Auger peaks are strongly affected by extrinsic excitations due to electron transport out of the surface and to intrinsic excitations induced by the sudden creation of the two static core holes. Following a method developed for XPS in a previous work [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17], we have calculated the effective energy-differential inelastic electron scattering cross-sections, including the effects of the surface and of the two core holes, within the dielectric response theory by means of the QUEELS-XPS software (QUantitative analysis of Electron Energy Losses at Surfaces for XPS). The Auger spectra are then modeled by convoluting this energy loss cross section with the primary excitation spectrum that accounts for all effects which are part of the initial Auger process, i.e. L-S coupling and vacancy satellite effects. The shape of this primary excitation spectrum is fitted to get close agreement between the theoretical and the experimental spectra obtained from X-ray excited Auger electron spectroscopy (XAES). We have performed these calculations of XAES spectra for various LMM Auger transitions of pure Cu (L3M45M45, L3M23M45, L3M23M23 and L2M45M45 transitions). We compare the resulting primary excitation spectra with theoretical results published in the literature and obtain reasonable quantitative agreement. In particular, we extract from experimental spectra quantitative intensities due to Coster-Kronig, shake-off and shake-up processes relative to the intensity from the “normal” Auger process.

Pauly, N.; Tougaard, S.; Yubero, F.

2014-12-01

308

Spin Excitations in Fe(Se,Te)  

NASA Astrophysics Data System (ADS)

The full spectrum of magnetic excitations in both superconducting FeTe0.51Se0.49 (x=0.49) and non- superconducting Fe1.04Te0.73Se0.27 (x=0.27) was studied using inelastic neutron scattering on single crystal samples. The magnetic excitations are two-dimensional in nature and are observed for energy transfers as high as 300 meV. The zero energy extrapolation of the measured dispersion shows incommensurate excitations emanating from a wavevector near (0.5,0.5), the location of the resonance in the superconducting material. For low energy transfers, the spectrum consists of a set of incommensurate spots, four-fold symmetric about the (1,0) (square lattice (?,?)) wavevector. At higher energies, these spots evolve into rings centered on Q=(1,0). These excitations are notably different than the cones of scattering expected from a long-range magnetically ordered material and likely reflect the itinerant nature of the magnetism. The qualitative evolution of the incommensurate excitation spectrum is similar that seen previously in the cuprates. Despite the incommensurate nature of the spectrum, the observed resonance in the x=0.49 sample remains peaked at the (0.5,0.5) wavevector as in other Fe-based superconductors. At low energies, the x=0.27 sample exhibits an additional feature in the excitation spectrum centered near Q=(0.5,0), the wavevector of magnetic order in Fe1+yTe. This scattering persists for all energies below about 10 meV and forms the short range order observed for this concentration. This scattering is completely absent in the x=0.49 sample which contains no excess Fe.

Lumsden, Mark

2011-03-01

309

Science Shy, Science Savvy, Science Smart.  

ERIC Educational Resources Information Center

Science-shy public served by science-shy Congress could threaten national and global survival. People will come to understand science and technology when actively experiencing these disciplines as they exist in reality; where they have power and beauty, rather than in educational frameworks; where they are often neutered. Fortunately, "real stuff"…

Fort, Deborah C.

1993-01-01

310

Bridging Science and Policy: The AGU Science Policy Conference  

NASA Astrophysics Data System (ADS)

In recent years, science has become inextricably linked to the political process. As such, it is more important now than ever for science to forge a better relationship with politics, for the health of both science and society. To help meet this need, the American Geophysical Union (AGU) strives to engage its members, shape policy, and inform society about the excitement of Earth and space science and its role in developing solutions for the sustainability of the planet. In June 2013, AGU held its second annual Science Policy Conference in Washington, D.C. The goal of the conference is to provide a new forum for diverse discussions and viewpoints on the challenges and opportunities of science policy, with a focus on applications of Earth and space science that serve local, national, and international communities. The meeting brought together more than 300 scientists, policy makers, industry professionals, members of the press, and other stakeholders to discuss the topics concerning the Arctic, climate change, oceans, energy, technology and infrastructure, and natural hazards science as they relate to challenges impacting society. Sessions such as 'The Water-Energy Nexus,' 'Potential for Megadisasters,' 'The Changing Ocean and Impacts on Human Health,' and 'Drowning and Drought: Agricultural Impacts of Climate Change' are examples of some of the intriguing and timely science policy issues addressed at the conference. The findings from the conference were used to develop a summary report. The report highlights key facts and figures to be used as a resource in discussions with policy makers and other stakeholders regarding the conference topics. This presentation will discuss the goals and outcomes of the conference and how the event represents one of the many ways AGU is approaching its 'Science and Society' priority objective as part of the Union's strategic plan; namely by increasing the effectiveness and recognition of AGU among policy makers as an authoritative source of integrated, interdisciplinary Earth and space science information.

Hankin, E. R.; Uhlenbrock, K.; Landau, E. A.

2013-12-01

311

Excitation of confined modes on particle arrays  

E-print Network

We describe both theoretically and experimentally the existence and excitation of confined modes in planar arrays of gold nanodisks. Ordered 2D lattices of monodispersive nanoparticles are manufactured, embedded in a silica matrix, and exposed to evanescent prism-coupling illumination, leading to dark features in the reflectivity, which signal the presence of confined modes guided along the arrays. We find remarkable agreement between theory and experiment in the frequency-momentum dispersion of the resonances. Direct excitation of these modes reveals long propagation distances and deep extinction features. This characterization of guided modes shows the great potential of metallic particle arrays for optical signal processing and distant sensing applications.

Bendaña, Xesús Manoel; Pirruccio, Giuseppe; Rivas, Jaime Gómez; de Abajo, F Javier García

2012-01-01

312

Formalism of collective electron excitations in fullerenes  

E-print Network

We present a detailed formalism for the description of collective electron excitations in fullerenes in the process of the electron inelastic scattering. Considering the system as a spherical shell of a finite width, we show that the differential cross section is defined by three plasmon excitations, namely two coupled modes of the surface plasmon and the volume plasmon. The interplay of the three plasmons appears due to the electron diffraction of the fullerene shell. Plasmon modes of different angular momenta provide dominating contributions to the differential cross section depending on the transferred momentum.

Verkhovtsev, Alexey V; Solov'yov, Andrey V

2012-01-01

313

Laser pulses for coherent xuv Raman excitation  

E-print Network

We combine multi-channel electronic structure theory with quantum optimal control to derive Raman pulse sequences that coherently populate a valence excited state. For a neon atom, Raman target populations of up to 13% are obtained. Superpositions of the ground and valence Raman states with a controllable relative phase are found to be reachable with up to 4.5% population and phase control facilitated by the pump pulse carrier envelope phase. Our results open a route to creating core-hole excitations in molecules and aggregates that locally address specific atoms and represent the first step towards realization of multidimensional spectroscopy in the xuv and x-ray regimes.

Greenman, Loren; Whaley, K Birgitta

2014-01-01

314

Exciting Baryons: now and in the future  

SciTech Connect

This is the final talk of NSTAR2011 conference. It is not a summary talk, but rather a looking forward to what still needs to be done in excited baryon physics. In particular, we need to hone our tools connecting experimental inputs with QCD. At present we rely on models that often have doubtful connections with the underlying theory, and this needs to be dramatically improved, if we are to reach definitive conclusions about the relevant degrees of freedom of excited baryons. Conclusions that we want to have by NSTAR2021.

Michael Pennington

2012-04-01

315

Stability of excited bosonic stellar configurations  

NASA Astrophysics Data System (ADS)

In this paper I study the problem of the dynamical stability of Bose star configurations which correspond to excited states. In particular I show that the eigenvalues of the pulsation equation, which governs the time evolution of the infinitesimal radial oscillations, are real. This, together with the theorem, proved by Lee and Pang, that for a configuration with critical central density ?crit the pulsation equation has a zero mode and the fact that for central densities much smaller than ?crit the lowest eigenvalue is positive, leads to the conclusion that the excited Bose star configurations are classically stable for central densities up to ?crit.

Jetzer, Ph.

1989-05-01

316

Using Visits to Interactive Science and Technology Centers, Museums, Aquaria and Zoos To Promote Learning in Science.  

ERIC Educational Resources Information Center

Interactive science and technology centers are flourishing throughout the world. Displays in museums, aquaria and zoos are becoming much more interactive. These places offer exciting opportunities for school children to experience science and technology in a stimulating environment. But do such centers affect learning? Do they offer valuable…

Rennie, Leonie J.; McClafferty, Terence P.

317

Science Sacks  

ERIC Educational Resources Information Center

With the emphasis placed on standardized testing, science education has been squeezed out. As a physics teacher, the author knows the importance of building children's interest in science early in their school career and of providing practice in basic science skills and inquiry. In order to make more time for science at her sons' elementary…

Freudenberg, Kimberlee

2012-01-01

318

Physical Science  

NSDL National Science Digital Library

Physical science is the science of matter and energy and their interactions and examines the physical world around us. Using the methods of the physical sciences, students learn about the composition, structure, properties, and reactions of matter and the relationships between matter and energy. Students are best able to build understanding of the physical sciences through hands-on exploration of the physical world.

K-12 Outreach,

319

Science Shorts: Spoilage Science  

NSDL National Science Digital Library

Whether it's fresh or processed, all food eventually spoils. Methods such as freezing, canning, and the use of preservatives lengthen the lifespan of foods, and we--and the modern food industry--rely on these methods to maintain our food supply. This month's Science Shorts explores the concepts of food spoilage and prevention.

2005-01-01

320

Soapy Science. Teaching Science.  

ERIC Educational Resources Information Center

Describes a science and math activity that involves bubbles, shapes, colors, and solid geometry. Students build geometric shapes with soda straws and submerge the shapes in soapy water, allowing them to review basic geometry concepts, test hypotheses, and learn about other concepts such as diffraction, interference colors, and evaporation. (TJQ)

Leyden, Michael

1997-01-01

321

SCIENCE FESTIVALS Celebrating Science  

E-print Network

: the World Science Festival in New York City (1, 2). Named with characteristic American hubris, the activities in New York were as much a "world" festival as baseball's "World Series" is a true world Day, a former TV producer), attendees were treated to events that included scientist- presenters

Rhoads, James

322

Outreach Coordination for the Plasma Sciences  

Microsoft Academic Search

Outreach for the plasma sciences has adapted to multiple levels and venues for communicating the excitement and possibilities of the field. The internet and web are the most important new media for such public outreach. Nevertheless, a variety of outreach methods and coordination efforts will always be valuable because of their various strengths and weaknesses and the need to address

Timothy Eastman

2001-01-01

323

Safer Science: Building Safety in Foreign Language  

NSDL National Science Digital Library

A school is about to undergo major renovations and new construction to handle a growing student population. So some science classes and labs are assigned to other parts of the building temporarily. Most teachers are excited about the opportunity to help d

Roy, Ken

2011-01-01

324

How Do You Choose Science Trade Books?  

NSDL National Science Digital Library

Using trade books is one strategy that has the potential to increase students' interest and achievement in science; to enhance scientific and technological literacy; and to help open doors to exciting careers. Because there are over 120,000 children's tra

Dudley, Ann P.; Williams, Christy S.; Rice, Diana C.

2001-03-01

325

Science Playwiths  

NSDL National Science Digital Library

Science Playwiths consists of a set of small experiments using simple everyday science, selected for quick, easy use by K-6 teachers. Topics include Earth science, physics, electricity and magnetism, fluid flow, sound, light, and others. There is also a set of more complex experiments, methods and enquiries; an Australian science and technology timeline; a set of ideas for science projects and some help; and "The Ugly Islands", a simulation exercise that offers problems for people to play with.

Macinnis, Peter

326

Communicating Science through Exhibitions  

NASA Astrophysics Data System (ADS)

It is critically important for the public to better understand the scientific process. Museum exhibitions are an important part of informal science education that can effectively reach public audiences as well as school groups. They provide an important gateway for the public to learn about compelling scientific endeavors. Science exhibitions also provide a marvelous opportunity for scientists to become engaged in the exhibit development process. The Space Science Institute (SSI) is a national leader in producing traveling science exhibitions and their associated educational programming (i.e. interactive websites, educator workshops, public talks, instructional materials). The focus of this presentation will be on two of its exhibit projects: MarsQuest (on tour for four years) and Alien Earths (its tour began early in 2005). MarsQuest is enabling millions of Americans to share in the excitement of the scientific exploration of Mars and to learn more about their own planet in the process. Alien Earths will bring origins-related research and discoveries to students and the American public. It has four interrelated exhibit areas: Our Place in Space, Star Birth, Planet Quest, and Search for Life. Exhibit visitors will explore the awesome events surrounding the birth of stars and planets; they will join scientists in the hunt for planets outside our solar system including those that may be in ``habitable zones'' around other stars; and finally they will be able to learn about how scientists are looking for signs of life beyond Earth. SSI is also developing interactive web sites based on exhibit themes. New technologies are transforming the Web from a static medium to an interactive environment with tremendous potential for informal education and inquiry-based investigations. This talk will focus on the role informal science projects play in effectively communicating science to a broad, public audience.

Dusenbery, Paul

2005-04-01

327

[Faculty of Science Information and Computing Sciences  

E-print Network

[Faculty of Science Information and Computing Sciences] Terminating combinator parsers in Agda and Computing Sciences Utrecht University June 12, 2008 #12;[Faculty of Science Information and Computing Sciences] 2 Overview Totality Parser combinators Terminating combinator parsers #12;[Faculty of Science

Löh, Andres

328

Faculty of Science Science Undergraduate  

E-print Network

Faculty of Science Science Undergraduate Research Awards (SURA) What are Science Undergraduate by an endowment provided by the estate of the late Eva Moody allows the Faculty of Science to provide a number are directed at undergraduate students who wish to carry out a research project during the summer under

Pedersen, Tom

329

Cognitive Science 1 Cognitive Science  

E-print Network

), David Rand (Psychology), Gregory Samanez-Larkin (Psychology) Lecturer Kathryn Davidson Cognitive scienceCognitive Science 1 Cognitive Science Director of undergraduate studies: Joshua Knobe, 102 C, 432-1699, joshua.knobe@yale.edu; www.yale.edu/cogsci FACULTY ASSOCIATED WITH THE PROGRAM IN COGNITIVE SCIENCE

330

Natural Sciences Tripos EARTH SCIENCES  

E-print Network

Natural Sciences Tripos EARTH SCIENCES University of Cambridge Undergraduate Prospectus 2013.indd 1Undergraduate Prospectus 2013.indd 1 29/07/2013 16:44:3529/07/2013 16:44:35 #12;Department of Earth Sciences in the future? These are some of the big questions that we seek to answer in our courses on Earth Sciences

Cambridge, University of

331

Faculty of Science Computer Science  

E-print Network

Faculty of Science Computer Science Software engineering, network and system analysis continue a variety of computer science programs to prepare students for a career in the technology industry or in research and academia. A computer science degree provides an in-depth understanding of the fundamentals

332

Faculty of Science Computer Science  

E-print Network

) Multimedia - emphasizes WWW, visualization and human computer interface; courses in Computer Science canFaculty of Science Computer Science Computer software engineering, network and system analysis.uwindsor.ca/computerscience The University of Windsor offers a variety of computer science programs to prepare students for a career

333

Science Fiction and Science Education.  

ERIC Educational Resources Information Center

Uses science fiction films such as "Jurassic Park" or "Anaconda" to teach science concepts while fostering student interest. Advocates science fiction as a teaching tool to improve learning and motivation. Describes how to use science fiction in the classroom with the sample activity Twister. (YDS)

Cavanaugh, Terence

2002-01-01

334

Nuclear excitation and precompound nuclear reactions  

SciTech Connect

The angular distribution of nucleons emitted in nucleon-induced precompound nuclear reactions are calculated taking into account the effect of excitation on the kinematics of nucleon-nucleon scattering inside the target-plus-projectile system. The results are compared with quantum mechanical calculations and those of reaction models based on a pure nucleon-nucleon collision picture.

De, A.; Ray, S.; Ghosh, S.K.

1988-06-01

335

Persistent Histamine Excitation of Glutamatergic Preoptic Neurons  

PubMed Central

Thermoregulatory neurons of the median preoptic nucleus (MnPO) represent a target at which histamine modulates body temperature. The mechanism by which histamine excites a population of MnPO neurons is not known. In this study it was found that histamine activated a cationic inward current and increased the intracellular Ca2+ concentration, actions that had a transient component as well as a sustained one that lasted for tens of minutes after removal of the agonist. The sustained component was blocked by TRPC channel blockers. Single-cell reverse transcription-PCR analysis revealed expression of TRPC1, TRPC5 and TRPC7 subunits in neurons excited by histamine. These studies also established the presence of transcripts for the glutamatergic marker Vglut2 and for the H1 histamine receptor in neurons excited by histamine. Intracellular application of antibodies directed against cytoplasmic sites of the TRPC1 or TRPC5 channel subunits decreased the histamine-induced inward current. The persistent inward current and elevation in intracellular Ca2+ concentration could be reversed by activating the PKA pathway. This data reveal a novel mechanism by which histamine induces persistent excitation and sustained intracellular Ca2+ elevation in glutamatergic MnPO neurons. PMID:23082195

Tabarean, Iustin V.

2012-01-01

336

Excited Heavy Mesons from QCD Sum Rules  

E-print Network

Orbitally excited L=1 charm mesons are studied by QCD sum rules in the framework of heavy quark effective theory. The meson masses and the strong decay widths are obtained. This talk is based on our works of refs. 1 and 2 collaborated with Y.B. Dai, C.S. Huang, M.Q. Huang and H.Y. Jin.

Chun Liu

1998-02-03

337

Voltage regulators for self excited induction generator  

Microsoft Academic Search

When an induction machine is driven from external prime mover at a speed greater than synchronous speed, it acts as induction generator provided reactive power is supplied. This reactive current generates required magnetic field for self-excitation of induction generator (seig). The induction generator thus produced has poor voltage regulation. To get better voltage regulation the reactive current need to be

T. Chandra Sekhar; Bishnu P. Muni

2004-01-01

338

Quasiparticle theory of electron excitations in solids  

Microsoft Academic Search

A first-principles quasiparticle approach to electron excitation energies in solids is reviewed. The theory has been applied to explain and predict the spectroscopic properties of a variety of systems including bulk crystals, surfaces, interfaces, clusters, defects, and materials under pressure. Several illustrative applications are presented and some recent theoretical developments discussed.

1995-01-01

339

Homopolar and bipolar hybrid excitation synchronous machines  

Microsoft Academic Search

This paper presents a description and operating principle of different hybrid excitation synchronous machines. Four prototype machines of different power rating (3 kW and 15 kW) have been studied. These machines combine two flux sources: permanent magnets, located in the rotor, and field coils, located in the stator. Thanks to this particular configuration the air gap flux can be easily

L. Vido; M. Gabsi; M. Lecrivain; Y. Amara; F. Chabot

2005-01-01

340

Excitation system for rotating synchronous machines  

DOEpatents

A system for providing DC current to a rotating superconducting winding is provided. The system receives current feedback from the superconducting winding and determines an error signal based on the current feedback and a reference signal. The system determines a control signal corresponding to the error signal and provides a positive and negative superconducting winding excitation voltage based on the control signal.

Umans, Stephen D. (Belmont, MA); Driscoll, David J. (South Euclid, OH)

2002-01-01

341

Cherenkov like mechanism of surface wave excitation  

E-print Network

The theory is presented of surface wave excitation by a fast moving charged particle in a thin uniform metal film surrounded by a dielectric medium. It is shown that the Vavilov-Cherenkov like effect for the sufface waves could arise for particles whose velocities are ten- and even hundred-times lower than the corresponding velocities in a uniform medium.

Zuev, V S

2009-01-01

342

Surface plasmon excitation by a quantum oscillator  

E-print Network

Surface waves in a thin uniform metal film are described in terms of quantum electrodynamics.The interaction of surface waves with a quantum oscillator is discussed in the dipole approximation. The increase in the spontaneous emission rate of the excited quantum oscillator, the so called Purcell factor, is evaluated to be as high as by 10 to the five times.

Lidsky, V V

2009-01-01

343

Contour Line Portraits: Excited about Artistic Abilities  

ERIC Educational Resources Information Center

In this article, the author describes a self-portrait project that encouraged students, boosted their self-confidence, and got them excited about their artistic abilities--while producing amazing results. This lesson effectively develops artistic ability by compelling students to see that drawing is quite simply breaking down objects into the…

Neal, Kari Gertz

2012-01-01

344

An Improved Electrically Excited Mercury Halide Laser.  

National Technical Information Service (NTIS)

An improved electric-discharge-excited, mercury halide dissociation laser is operable on the (B-X) transitions in HgCl, HgBr, and HgI at 558, 502, and 443 nm respectively. The laser discharge cell is elongated and made from temperature-resistant silicon-g...

R. L. Burnham

1978-01-01

345

On the Electronically Excited States of Uracil  

SciTech Connect

Vertical excitation energies in uracil in the gas phase and in water solution are investigated by the equation-of-motion coupled-cluster and multi-reference configuration interaction methods. Basis set effects are found to be important for converged results. The analysis of electronic wave functions reveals that the lowest singlet states are predominantly of a singly excited character and are therefore well described by single-reference equation-of-motion methods augmented by a perturbative triples correction to account for dynamical correlation. Our best estimates for the vertical excitation energies for the lowest singlet n and are 5.0±0.1 eV and 5.3±0.1 eV, respectively. The solvent effects for these states are estimated to be +0.5 eV and ±0.1 eV, respectively. We attribute the difference between the computed vertical excitations and the maximum of the experimental absorption to strong vibronic interaction between the lowest A00 and A0 states leading to intensity borrowing by the forbidden transition.

Epifanovsky, Evgeny; Kowalski, Karol; Fan, Peng-Dong; Valiev, Marat; Matsika, Spiridoula; Krylov, Anna

2008-10-09

346

Excited glue and the vibrating flux tube  

E-print Network

Recent lattice results for the energy of gluonic excitations as a function of quark separation are shown to correspond to transverse relativistic flux tube vibration modes. For large quark separations all states appear to degenerate into a few categories which are predicted uniquely, given the ground state.

Theodore J. Allen; M. G. Olsson; Sinisa Veseli

1998-04-29

347

Husimi Functions of Excited Squeezed Vacuum States  

NASA Astrophysics Data System (ADS)

Based on the Husimi operator in pure state form introduced by Fan et al., which is a squeezed coherent state projector, and the technique of integration within an ordered product (IWOP) of operators, as well as the entangled state representations, we obtain the Husimi functions of the excited squeezed vacuum states (ESVS) and two marginal distributions of the Husimi functions of the ESVS.

Meng, Xiang-Guo; Wang, Ji-Suo; Liang, Bao-Long

2009-09-01

348

Excited charmonium physics from lattice QCD  

SciTech Connect

Properties of excited mesons are studied using a lattice QCD simulation of a system comparable to charmonium. We extract a spectrum of states, including those with manifestly exotic quantum numbers. Radiative transition form-factors are also computed, in particular the transition from exotic ·c1 to J /È ³ which is found to be large on the usual scale of magnetic dipole transitions.

Jozef Dudek

2009-12-01

349

Exploring Excited Hadrons in Lattice QCD  

E-print Network

Progress in extracting the spectrum of excited hadron resonances in lattice QCD Monte Carlo calculations is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations with lighter pion masses are done is discussed, and the need for all-to-all quark propagators is emphasized.

Morningstar, Colin

2009-01-01

350

Exploring Excited Hadrons in Lattice QCD  

E-print Network

Progress in extracting the spectrum of excited hadron resonances in lattice QCD Monte Carlo calculations is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations with lighter pion masses are done is discussed, and the need for all-to-all quark propagators is emphasized.

Colin Morningstar; for the Hadron Spectrum Collaboration

2009-05-27

351

Critical phenomena in globally coupled excitable elements  

NASA Astrophysics Data System (ADS)

Critical phenomena in globally coupled excitable elements are studied by focusing on a saddle-node bifurcation at the collective level. Critical exponents that characterize divergent fluctuations of interspike intervals near the bifurcation are calculated theoretically. The calculated values appear to be in good agreement with those determined by numerical experiments. The relevance of our results to jamming transitions is also mentioned.

Ohta, Hiroki; Sasa, Shin-Ichi

2008-12-01

352

STABLE PLASMA JET FOR EXCITATION OF SOLUTIONS  

Microsoft Academic Search

A plasma jet, as adapted for the spectrochemical excitation of solutions ; and used with a photoelectric spectrometer to measure light intenslties, is ; described. Included is the design, construction, part specifications, operation, ; and performanoe of the stable plasma jot. The jet has a tungsten rod as an ; external, yet integral, cathodic electrode. The stabilized jet promises full

Louis E. Owen

1961-01-01

353

Self Excitation of Nano-Mechanical Pillars  

Microsoft Academic Search

Self excitation is a mechanism which is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators [1], where a good example are the overall visible wind farm turbines [2]. In other words, a static force, like wind acting on the rotor blades, can generate a

Hyun S. Kim; Hua Qin; Robert H. Blick

2007-01-01

354

Electron Impact Excitation and Ionization of Neon  

NASA Astrophysics Data System (ADS)

We have further developed the B-Spline R-matrix (BSR) code [1] to allow for a large number of pseudo-states in the close-coupling expansion. In the present work, the BSRMPS approach [2] was employed to perform semi-relativistic (Breit-Pauli) close-coupling calculations for elastic scattering, excitation, and ionization of neon from both the ground state and the metastable excited states. Coupling to the ionization continuum through the pseudo-states is important for low-energy elastic scattering (to represent polarizability effects), for excitation in the ``intermediate'' energy regime of about 1-5 times the ionization potential, and to allow for the calculation of ionization processes by transforming the results obtained for excitation of the positive-energy pseudo-states. The current results represent a significant extension of our earlier near-threshold work [3] and previous non-relativistic RMPS calculations [4,5].[4pt] [1] O. Zatsarinny, Comp. Phys. Commun. 174 (2006) 273.[0pt] [2] O. Zatsarinny and K. Bartschat, Phys. Rev. Lett. 107 (2011) 023203.[0pt] [3] O. Zatsarinny and K. Bartschat, J. Phys. B 37 (2004) 2173.[0pt] [4] C. P. Ballance and D. C. Griffin, J. Phys. B 37 (2004) 2943.[0pt] [5] C. P. Ballance et al., J. Phys. B 37 (2004) 4779.

Zatsarinny, Oleg; Bartschat, Klaus

2012-10-01

355

Optical excitation of surface plasmons: An introduction  

Microsoft Academic Search

Beginning from low level concepts the basic understanding for the optical excitation of surface plasmons is developed. Prism coupling using the attenuated total reflection technique is discussed as well as the less traditional grating coupling technique. A brief discussion of some recent developments using twisted gratings is also presented. Finally a short summary of the potential device applications is given.

J. R. Sambles; G. W. Bradbery; Fuzi Yang

1991-01-01

356

Atomic-excitation effects on nuclear reactions  

SciTech Connect

Atomic-excitation effects arising from sudden nuclear recoil are shown to be a significant factor in broadening the 14.23-MeV resonance in /sup 12/C(p,p)/sup 12/C measured with a high--energy-resolution polarized beam. The total width of the resonance is found to be 1010 +- 30 eV.

Thompson, W.J.; Wilkerson, J.F.; Clegg, T.B.; Feagin, J.M.; Ludwig, E.J.; Merzbacher, E.

1980-09-01

357

a Class of Collective Excitations of the Hubbard Model:. ? Excitation of the Negative-U Model  

NASA Astrophysics Data System (ADS)

In this series of papers we present a detailed study of the particle-particle collective excitations of the Hubbard model, and their contribution to the density and spin excitation spectrum. In the first paper, we shall investigate the singlet particle-particle pair with momentum (?, ?), the ? particle, of the negative-U Hubbard model. We review three previously obtained theorems about the ? particle and develop a self-consistent linear response theory which takes into account its contribution to the density excitation spectrum in the superconducting state. We show that this self-consistent theory agrees with the exact theorems as well as the results of numerical Monte Carlo simulations.

Demler, Eugene; Zhang, Shou-Cheng; Bulut, Nejat; Scalapino, Douglas J.

358

Library of FT-Raman spectra of pigments, minerals, pigment media and varnishes, and supplement to existing library of Raman spectra of pigments with visible excitation  

Microsoft Academic Search

Sixty pigments, minerals and media have been analysed by Fourier-transform Raman (FT-Raman) microscopy in order to assemble a database of reference FT-Raman spectra for scientists working at the Arts–Science interface. An earlier library of Raman spectra compiled using visible excitation has been extended by the addition of 22 further reference spectra obtained with 780.0, 647.1, 632.8 and\\/or 514.5 nm excitation.

Lucia Burgio; Robin J. H Clark

2001-01-01

359

Cascadable excitability in optically injected microdisks  

NASA Astrophysics Data System (ADS)

All-optical spiking neural networks would allow high speed parallelized processing of time-encoded information, using the same energy efficient computational principles as our brain. As the neurons in these networks need to be able to process pulse trains, they should be excitable. Using simulations, we demonstrate Class 1 excitability in optically injected microdisk lasers, and propose a cascadable optical spiking neuron design. The neuron has a clear threshold and an integrating behavior. In addition, we show that the optical phase of the input pulses can be used to create inhibitory, as well as excitatory perturbations. Furthermore, we incorporate our optical neuron design in a topology that allows a disk to react on excitations from other disks. Phase tuning of the intermediate connections allows to control the disk response. Additionally, we investigate the sensitivity of the disk circuit to deviations in driving current and locking signal wavelength detuning. Using state-of-the-art fabrication techniques for microdisk laser, the standard deviation of the lasing wavelength is still about one order of magnitude too large. Finally, as the dynamical behavior of the microdisks is identical to the behavior in Semiconductor Ring Lasers (SRL), we compare the excitability mechanism due to optically injection with the previously proposed excitability due to asymmetry in the intermodal coupling in SRLs, as the latter mechanism can also be induced in disks due to, e.g., asymmetry in the external reaction. In both cases, the symmetry between the two counter-propagating modes of the cavity needs to be broken to prevent switching to the other mode, and allow the system to relax to its initial state after a perturbation. However, the asymmetry due to optical injection results in an integrating spiking neuron, whereas the asymmetry in the intermodal coupling is known to result in a resonating spiking neuron.

Van Vaerenbergh, Thomas; Alexander, Koen; Fiers, Martin; Mechet, Pauline; Dambre, Joni; Bienstman, Peter

2014-05-01

360

Tuned Thalamic Excitation is Amplified by Visual Cortical Circuits  

PubMed Central

Cortical neurons in thalamic recipient layers receive excitation from the thalamus and the cortex. The relative contribution of these two sources of excitation to sensory tuning is poorly understood. Here we optogenetically silence the visual cortex of mice to isolate thalamic excitation onto layer 4 neurons during visual stimulation. Thalamic excitation contributes to a third of total excitation and is organized in spatially offset, yet overlapping ON and OFF receptive fields. This receptive field structure predicts the orientation tuning of thalamic excitation. Finally, thalamic and total excitation are similarly tuned to orientation and direction, and have the same temporal phase relationship to the visual stimulus. Our results indicate that tuning of thalamic excitation is unlikely to be imparted by direction or orientation selective thalamic neurons and that a principal role of cortical circuits is to amplify tuned thalamic excitation. PMID:23933748

Lien, Anthony D.; Scanziani, Massimo

2013-01-01

361

iBiology: communicating the process of science  

PubMed Central

The Internet hosts an abundance of science video resources aimed at communicating scientific knowledge, including webinars, massive open online courses, and TED talks. Although these videos are efficient at disseminating information for diverse types of users, they often do not demonstrate the process of doing science, the excitement of scientific discovery, or how new scientific knowledge is developed. iBiology (www.ibiology.org), a project that creates open-access science videos about biology research and science-related topics, seeks to fill this need by producing videos by science leaders that make their ideas, stories, and experiences available to anyone with an Internet connection. PMID:25080124

Goodwin, Sarah S.

2014-01-01

362

FDTD simulation of field performance in reverberation chamber excited by two excitation antennas  

NASA Astrophysics Data System (ADS)

The excitation source is one of the critical items that determine the electromagnetic fields in a reverberation chamber (RC). In order to optimize the electromagnetic fields performance, a new method of exciting RC with two antennas is proposed based on theoretical analysis. The full 3D simulation of RC is carried out by the finite difference time domain (FDTD) method on two excitation conditions of one antenna and two antennas. The broadband response of RC is obtained by fast Fourier transformation (FFT) after only one simulation. Numerical data show that the field uniformity in the test space is improved on the condition of two transmitting antennas while the normalized electric fields decreased slightly compared to the one antenna condition. It is straightforward to recognize that two antennas excitation can reduce the demands on power amplifier as the total input power is split among the two antennas, and consequently the cost of electromagnetic compatibility (EMC) test in large-scale RC can be reduced.

Wang, Song; Wu, Zhan-cheng; Cui, Yao-zhong

2013-03-01

363

Production of excited double hypernuclei via Fermi breakup of excited strange systems  

E-print Network

Precise spectroscopy of multi-strange hypernuclei provides a unique chance to explore the hyperon-hyperon interaction. In the present work we explore the production of excited states in double hypernuclei following the micro-canonical break-up of an initially excited double hypernucleus which is created by the absorption and conversion of a stopped $\\Xi^{-}$ hyperon. Rather independent on the spectrum of possible excited states in the produced double hypernuclei the formation of excited states dominates in our model. For different initial target nuclei which absorb the $\\Xi^-$, different double hypernuclei nuclei dominate. Thus the ability to assign the various observable $\\gamma$-transitions in a unique way to a specific double hypernuclei by exploring various light targets as proposed by the {\\Panda} collaboration seems possible. We also confront our predictions with the correlated pion spectra measured by the E906 collaboration.

Alicia Sanchez Lorente; Alexander Botvina; Josef Pochodzalla

2011-02-01

364

Optimization of Two-photon Excited Fluorescence Enhancement between Tunable and Broadband Femtosecond Laser Pulse Excitations  

E-print Network

140 fs pulse excitations using three dye-phantoms (Indo-1, FITC, and TRITC) representative of fluorescent probes with similar TPEF characteristics. The integrated experimental system, with custom-designed GDD compensation, dispersion-less laser...

Wang, Chao

2012-02-14

365

Waking-up to Science!  

NASA Astrophysics Data System (ADS)

The Science on Stage festival as an alarm clock for science teaching How is Europe to tackle its shortage of scientists? The EIROforum Science on Stage festival aims to give European teachers some of the answers they need to take up this urgent challenge. This unique event, showcasing the very best of today's science education, will feature science demonstrations, a science teaching fair with some 66 stands, and a Round Table discussion with the participation of the European Commissioner for Science and Research, Janez Poto?nik. ESO PR Photo 14/07 ESO PR Photo 14/07 Science on Stage will have the city of Grenoble (France) buzzing from 2 to 6 April 2007. A rugby team and a hockey team will take on the power of the vacuum, a cook will demonstrate how science can inspire new culinary ideas, visitors will discover the real colour of the sun, an inflatable model of Borromini's gallery will help to explain the science of optical illusions, and Merlin himself will reveal all about how to make a cake float. These are just some of the exciting things that will be happening at the EIROforum Science on Stage festival. By showing how fascinating and entertaining science can be, the event aims to attract young people to science and ultimately help to reduce the shortage of scientists in Europe. With support from the European Commission, this international festival will bring together some 500 science educators from 27 European countries. The highlight of the festival will be a Round Table discussion on 'Science Education in the Age of the Knowledge Society - Strengthening Science Education in Europe', which will take place on 5 April 2007 with the participation of the European Commissioner for Science and Research, Janez Poto?nik. The panellists - all high-ranking decision-makers - will include the Danish Minister for Education, Bertel Haarder, the MEP Vittorio Prodi, and the Chair of the UK's Engineering and Physical Sciences Research Council, Julia Higgins. "Curiosity is in our genes", says Poto?nik. "Unfortunately it tends to die away when we grow up. This is because the ways we raise and educate our children and the ways we work and live do not always support innovative thinking and doing. We cannot change this overnight. But I think it is worth making the effort to awaken this dormant passion and initiatives like Science on Stage can be a very effective alarm clock", he adds. The festival will close with the presentation of the European Science Teaching Awards. The teaching materials and methods voted to be the best in Europe will then be presented in the 'Science in School' magazine, distributed free of charge to 30,000 teachers in Europe. The festival is the climax of a two-year programme of events organised in virtually every European country and from which delegates have been selected for their outstanding projects for promoting science. The winners of ESO's Catch a Star! 2007 contest will also be announced during the Science on Stage festival. The event follows on from the hugely successful 'Physics on Stage' and 'Science on Stage' festivals organised by EIROforum in 2000, 2002, 2003 and 2005. Journalists are cordially invited to take part in this unique European event. Practical information, including the detailed festival programme, is available on the Science on Stage web site at http://www.ill.fr/scienceonstage2007. A detailed press kit is available at http://www.ill.fr/scienceonstage2007/fichiers/SOSpresskit.pdf

2007-03-01

366

NASA/MSFC/NSSTC Science Communication Roundtable  

NASA Technical Reports Server (NTRS)

For the last several years the Science Directorate at Marshall Space Flight Center has carried out a diverse program of Internet-based science communication. The Directorate's Science Roundtable includes active researchers, NASA public relations, educators, and administrators. The Science@NASA award-winning family of Web sites features science, mathematics, and space news. The program includes extended stories about NASA science, a curriculum resource for teachers tied to national education standards, on-line activities for students, and webcasts of real-time events. Science stories cover a variety of space-related subjects and are expressed in simple terms everyone can understand. The sites address such questions as: what is space weather, what's in the heart of a hurricane, can humans live on Mars, and what is it like to live aboard the International Space Station? Along with a new look, the new format now offers articles organized by subject matter, such as astronomy, living in space, earth science or biology. The focus of sharing real-time science related events has been to involve and excite students and the public about science. Events have involved meteor showers, solar eclipses, natural very low frequency radio emissions, and amateur balloon flights. In some cases broadcasts accommodate active feedback and questions from Internet participants. Information will be provided about each member of the Science@NASA web sites.

Adams, Mitzi L.; Gallagher, D. L.; Koczor, R. J.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

367

High resolution fluorescent bio-imaging with electron beam excitation.  

PubMed

We have developed electron beam excitation assisted (EXA) optical microscope[1-3], and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.Figure 1(a) shows schematic diagram of the proposed EXA microscope. An electron beam is focused on a luminescent film. A specimen is put on the luminescent film directly. The inset in Fig. 1(a) shows magnified image of the luminescent film and the specimen. Nanometric light source is excited in the luminescent film by the focused electron beam. The nanometric light source illuminates the specimen, and the scattered or transmitted radiation is detected with a photomultiplier tube (PMT). The light source is scanned by scanning of the focused electron beam in order to construct on image. Figure 1(b) shows a luminescence image of the cells acquired with the EXA microscope, and Fig. 1(c) shows a phase contrast microscope image. Cells were observed in culture solution without any treatments, such as fixation and drying. The shape of each cell was clearly recognized and some bright spots were observed in cells. We believe that the bright spots indicated with arrows were auto-fluorescence of intracellular granules and light- grey regions were auto-fluorescence of cell membranes. It is clearly demonstrated that the EXA microscope is useful tool for observation of living biological cells in physiological conditions.jmicro;63/suppl_1/i16/DFU090F1F1DFU090F1Fig. 1.(a) Optical setup of EXA microscpe, and observation results of of living MARCO-expressing CHO cells with (b) EXA microscope and (c) phase contrast microscope. We proposed the EXA microscope as a technique with high spatial resolution beyond the diffraction limit of light. A spatial resolution greater than 100 nm was achieved for the EXA microscope and the dynamic behavior of moving nanoparticles in water was observed by time lapse imaging. We also demonstrated luminescence image of living cells in culture solution without any treatments. PMID:25359807

Kawata, Yoshimasa; Nawa, Yasunori; Inami, Wataru

2014-11-01

368

HEASARC - The High Energy Astrophysics Science Archive Research Center  

NASA Technical Reports Server (NTRS)

The High Energy Astrophysics Science Archive Research Center (HEASARC) is NASA's archive for high-energy astrophysics and cosmic microwave background (CMB) data, supporting the broad science goals of NASA's Physics of the Cosmos theme. It provides vital scientific infrastructure to the community by standardizing science data formats and analysis programs, providing open access to NASA resources, and implementing powerful archive interfaces. Over the next five years the HEASARC will ingest observations from up to 12 operating missions, while serving data from these and over 30 archival missions to the community. The HEASARC archive presently contains over 37 TB of data, and will contain over 60 TB by the end of 2014. The HEASARC continues to secure major cost savings for NASA missions, providing a reusable mission-independent framework for reducing, analyzing, and archiving data. This approach was recognized in the NRC Portals to the Universe report (2007) as one of the HEASARC's great strengths. This poster describes the past and current activities of the HEASARC and our anticipated developments in coming years. These include preparations to support upcoming high energy missions (NuSTAR, Astro-H, GEMS) and ground-based and sub-orbital CMB experiments, as well as continued support of missions currently operating (Chandra, Fermi, RXTE, Suzaku, Swift, XMM-Newton and INTEGRAL). In 2012 the HEASARC (which now includes LAMBDA) will support the final nine-year WMAP data release. The HEASARC is also upgrading its archive querying and retrieval software with the new Xamin system in early release - and building on opportunities afforded by the growth of the Virtual Observatory and recent developments in virtual environments and cloud computing.

Smale, Alan P.

2011-01-01

369

Dramatic Science  

NSDL National Science Digital Library

The setting: the science classroom. The characters: you and your students. The scene: Your students acting out scientific discoveries, modeling a frog's life cycle, mimicking the transition from liquid to solid. This is dramatic science , a teachi

Mcgregor, Debbie; Precious, Wendy

2010-10-01

370

Science Alive!  

NSDL National Science Digital Library

An elementary school brings in community volunteers for a full-day, all-school event focused on real world science. This article describes the planning process and types of science professionals and non-professionals recruited for the event.

Tally-Foos, Kay

2005-01-01

371

Science Sleuths.  

ERIC Educational Resources Information Center

Describes a two-day forensic science course that is offered to eighth grade students enrolled in Science, Mathematics, and Technology Magnet Schools. Provides sample student activity sheets for the course. (Author/RT)

Lilly, Sherril L.

1989-01-01

372

Forensic Science  

ERIC Educational Resources Information Center

A course is described, which was given during an interim, with an enrollment of 41 students. The course involved an in-depth study of forensic science, involving students with the methodology of science. (DF)

Berry, Keith O.; Nigh, W. G.

1973-01-01

373

Science Fiction and Science Literacy  

NSDL National Science Digital Library

Science fiction is read not only for enjoyment, but because it digs into scientific concepts with imagination, creativity, and a thorough appreciation of consequence. It has so much to offer in terms of good science and how science works, while at the same time addressing the basics of literacy. In this article, the author makes a case for why science fiction should be a part of science curricula and provides an all-purpose, critical reading activity to help teachers use science fiction in the classroom.

Czerneda, Julie E.

2006-02-01

374

Impulse excitation of piezoelectric bimorphs for energy harvesting: a dimensionless model  

NASA Astrophysics Data System (ADS)

Energy harvesting (EH) is a multidisciplinary research area, involving physics, materials science and engineering, with the objective of providing renewable sources of power sufficient to operate targeted low-power applications. Piezoelectric transducers are often used for inertial vibrational as well as direct excitation EH. However, due to the stiffness of the most common material (PZT), compact and light-weight harvesters have high resonant frequencies, making them inefficient at extracting low-frequency power from the environment. The technique of frequency up-conversion, in the form of either plucking or impulse excitation, aims to bridge this frequency gap. In this paper, the technique is modelled analytically with focus on impulse excitation via impact or shock. An analytical model is developed in a standard way starting from the Euler-Bernoulli beam equations adapted to a piezoelectric bimorph. A set of dimensionless variables and parameters is defined and a system of differential equations derived. Here the system is solved numerically for a wide range of the two group parameters present, covering piezoelectric coupling strength between PVDF and PMN-PT. One major result is that the strength of the coupling strongly affects the timescale of the process, but has only a minor effect on the total energy converted. The model can be readily adapted to different excitation profiles.

Pozzi, Michele

2014-04-01

375

Electrical Excitation of Surface Plasmon Polaritons  

NASA Astrophysics Data System (ADS)

A surface plasmon polariton (SPP) is an electromagnetic wave propagating at the interface between a metal and a dielectric material. The two-dimensional confinement of SPPs and the tunability of their dispersion enable optical functionality that cannot be achieved with regular dielectrics. Several novel concepts for sensing and opto-electronic integration based on SPPs have been proposed. In nearly all applications, as well as experiments based on SPPs, far-field excitation of SPPs is used, leading to bulky device designs. This thesis presents an electrically excitable source for SPPs that can be integrated in small, chip-size devices to enable the full application potential of SPPs. The device is based on a dielectric/metal geometry in which silicon quantum dots are placed in the near-field of the SPP mode. The quantum dots are electrically excited and decay by the generation of SPPs. Silicon quantum dots in silica are made by a magnetron sputtering technique, followed by annealing. From photoluminescence spectra as well as lifetime measurements we conclude that well-passivated Si quantum dots with quantum confined luminescence around 800 nm can be made. An electrical injection geometry is presented and electroluminescence is observed around 650 nm under a bias of 15-30 V. Strong bleaching of the quantum dot luminescence is observed under 0.5-20 keV electron beam irradiation, which has a potential consequence for the use of electron beam lithography in nanofabrication of structures with Si quantum dots. We describe the design and the fabrication of an electrically excitable plasmon source based on an insulator-metal-insulator (IMI) geometry. The coupling of quantum dots to the SPP mode was studied theoretically. For quantum dots spaced 20-200 nm away from the metal surface, more than 50% of the decay is into SPPs. An IMI SPP geometry for electrical excitation was fabricated using gold and silica doped with Si quantum dots as dielectric material. An IMI SPP source in the infrared region was fabricated by incorporating erbium in the dielectric material. Using an SPP waveguide coupled to the source, with suitable engineered outcoupling gratings, we observed the propagation and outcoupling of electrically excited SPPs. The optical properties of Si quantum dots in alumina are studied. This material is deposited by using CMOS compatible, low-temperature techniques of atomic layer deposition (ALD) and low pressure chemical vapor deposition (LPCVD). Quantum-confined photo- and electroluminescence is observed at 700-900 nm. This material is used in a novel metal-insulator-metal (MIM) geometry. SPPs are electrically excited and propagate inside the MIM geometry and are radiated into the far-field by an outcoupling structure. The radiated intensity decays for outcoupling structures further away from the excitation source. The obtained propagation length is = 4.4 0.6 micron, which is in good agreement with the expected propagation length based on measured values of the dielectric constants. The last chapter of this thesis reports on several application ideas for the electrical SPP sources presented in this thesis. Integrated lab-on-a-chip devices, plasmonic (bio)sensors, nanoscale photonic integrated circuits, and a novel quantum dot solar cell geometry are proposed.

van Loon, R. V. A.

2009-02-01

376

Quasiparticle excitations in Bose-Fermi mixtures  

SciTech Connect

We analyze the excitation spectrum of a three-dimensional Bose-Fermi mixture with tunable resonant interaction parameters and high hyperfine spin multiplets. We focus on a three-particle vertex describing fermionic and bosonic atoms which can scatter to create fermionic molecules or disassociate. For a single molecular level, in analogy to the single magnetic impurity problem we argue that the low-lying excitations of the mean-field theory are described by the Fermi-liquid picture with a quasiparticle weight and charge which is justified by a 1/N{sub {psi}}expansion, expected to be exact in the limit of infinite degeneracy (or very high fermionic spin) N{sub {psi}{yields}{infinity}}. Our emphasis is placed on the novel conditions for chemical equilibrium and how many-body chemical reactions renormalize the bosonic chemical potential, modifying condensation and superfluid-insulator transitions.

Akhanjee, Shimul [Condensed Matter Theory Laboratory, RIKEN, Wako, Saitama 351-0198 (Japan)

2010-08-15

377

Quasiparticle excitations in relativistic quantum field theory  

E-print Network

We analyze the particle-like excitations arising in relativistic field theories in states different than the vacuum. The basic properties characterizing the quasiparticle propagation are studied using two different complementary methods. First we introduce a frequency-based approach, wherein the quasiparticle properties are deduced from the spectral analysis of the two-point propagators. Second, we put forward a real-time approach, wherein the quantum state corresponding to the quasiparticle excitation is explicitly constructed, and the time-evolution is followed. Both methods lead to the same result: the energy and decay rate of the quasiparticles are determined by the real and imaginary parts of the retarded self-energy respectively. Both approaches are compared, on the one hand, with the standard field-theoretic analysis of particles in the vacuum and, on the other hand, with the mean-field-based techniques in general backgrounds.

Daniel Arteaga

2008-01-28

378

Excited nucleons with chirally improved fermions  

E-print Network

We study positive and negative parity nucleons on the lattice using the chirally improved lattice Dirac operator. Our analysis is based on a set of three operators chi_i with the nucleon quantum numbers but in different representations of the chiral group and with different diquark content. We use a variational method to separate ground state and excited states and determine the mixing coefficients for the optimal nucleon operators in terms of the chi_i. We clearly identify the negative parity resonances N(1535) and N(1650) and their masses agree well with experimental data. The mass of the observed excited positive parity state is too high to be interpreted as the Roper state. Our results for the mixing coefficients indicate that chiral symmetry is important for N(1535) and N(1650) states. We confront our data for the mixing coefficients with quark models and provide insights into the physics of the nucleon system and the nature of strong decays.

Dirk Broemmel; Peter Crompton; Christof Gattringer; Leonid Ya. Glozman; C. B. Lang; Stefan Schaefer; Andreas Schaefer

2003-07-05

379

The Tongue as an Excitable Medium  

E-print Network

Geographic tongue (GT) is a benign condition affecting approximately 2% of the population, whereby the papillae covering the upper part of the tongue are lost due to a slowly expanding inflammation. The resultant dynamical appearance of the tongue has striking similarities with well known phenomena observed in excitable media, such as forest fires, cardiac dynamics and chemically-driven reaction-diffusion systems. Here we explore the dynamics associated with GT from a dynamical systems perspective, utilizing cellular automata simulations. We emphasize similarities with other excitable systems as well as unique features observed in GT. Our results shed light on the evolution of the inflammation and contribute to the classification of the severity of the condition, based on the characteristic patterns observed in GT patients.

Seiden, Gabriel

2014-01-01

380

Liquid storage tanks under vertical excitation  

SciTech Connect

Until recently, the hydrodynamic effects on liquid storage tanks induced by an earthquake excitation were basically treated for the horizontal component of the earthquake. Recent studies, however, showed that the hydrodynamic effects due to the vertical component of an earthquake may be significant. In these studies the tank is assumed to be fixed at the bottom. This paper is concerned with the hydrodynamic behavior of liquid storage tanks induced by vertical earthquake input excitation. First, the fluid-tank system is treated as a fixed-base system and a simple formula is obtained for the coupled fluid-structure natural frequency. Second, additional interaction effects due to the foundation flexibility on the fluid-tank system are investigated. It is concluded that the foundation flexibility may have a significant effect on the hydrodynamic behavior of the liquid storage tanks under a vertical ground shaking.

Philippacopoulos, A.J.

1985-01-01

381

Normal intracortical excitability in developmental stuttering.  

PubMed

Persistent developmental stuttering (PDS) shares clinical features with task-specific dystonias. In these dystonias, intracortical inhibition is abnormally weak. We therefore sought to determine intracortical inhibition and intracortical facilitation in PDS. In 18 subjects with PDS since childhood (mean age, 39.4 [SD 13.0] years) and 18 speech-fluent controls (43.6 [14.3] years), we investigated resting and active motor thresholds as well as intracortical inhibition and facilitation of the optimal representation of the abductor digiti minimi of the dominant hand using transcranial magnetic stimulation. In PDS, the resting and active motor thresholds were increased, whereas intracortical inhibition and facilitation were normal. Normal intracortical excitability makes a pathophysiological analogy between focal dystonia and PDS less likely. The enhanced motor threshold suggests reduced motor cortical neuronal membrane excitability in PDS. PMID:12815664

Sommer, Martin; Wischer, Stephan; Tergau, Frithjof; Paulus, Walter

2003-07-01

382

Earth Rotational Variations Excited by Geophysical Fluids  

NASA Technical Reports Server (NTRS)

Modern space geodetic measurement of Earth rotation variations, particularly by means of the VLBI technique, has over the years allowed studies of Earth rotation dynamics to advance in ever-increasing precision, accuracy, and temporal resolution. A review will be presented on our understanding of the geophysical and climatic causes, or "excitations". for length-of-day change, polar motion, and nutations. These excitations sources come from mass transports that constantly take place in the Earth system comprised of the atmosphere, hydrosphere, cryosphere, lithosphere, mantle, and the cores. In this sense, together with other space geodetic measurements of time-variable gravity and geocenter motion, Earth rotation variations become a remote-sensing tool for the integral of all mass transports, providing valuable information about the latter on a wide range of spatial and temporal scales. Future prospects with respect to geophysical studies with even higher accuracy and resolution will be discussed.

Chao, Benjamin F.

2004-01-01

383

Localized excitations in UPdSn  

SciTech Connect

The authors have measured the inelastic neutron-scattering response of UPdSn at various temperatures using the HET and PHAROS spectrometers at the ISIS and MLNSC facilities, respectively. UPdSn shows some quasielastic scattering, which may be attributed to the hybridization of the 5f electrons with the conduction electrons. Furthermore, they find a clear excitation around 40meV above 40K in addition to the phonon contribution. While this excitation may be indicative of crystal fields in UPdSn, its strong temperature dependence seems to contradict a simple crystal-field picture. Below T{sub N}, the unusual temperature dependence may be attributed to magnetically-driven distortions (and subsequent changes in the local surrounding of the U ions), but there is some evidence that other additional mechanism(s) may contribute above T{sub N}. Some possible mechanisms will be discussed.

Nakotte, H.; Robinson, R.A.; Swan, T.; Kelley, T. [Los Alamos National Lab., NM (United States). Manuel Lujan Jr. Neutron Scattering Center; Bull, M. [Univ. of London (United Kingdom); [Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.; McEwen, K.A. [Univ. of London (United Kingdom); Ecclestone, R.A. [Rutherford Appleton Lab., Chilton (United Kingdom). ISIS Div.; Brueck, E. [Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.

1997-11-01

384

Calculations of coincident ionization plus excitation  

SciTech Connect

For Li- and Be-like ions, K x-ray yields, together with detection that the ionic charge has increased, give the cross section for ionization plus excitation (IE), a process which can exhibit electron-electron correlations. Measurements of IE for /sub 14/Si/sup 11 +/ + He stimulated our coupled-channels calculations in the independent-Fermi-particle model (IFPM), which includes Pauli correlations. We discuss how the IFPM expressions, generalized here to include an open shell, differ from those for distinguishable electrons. The sensitivity of sigma/sub IE/ to correlations is shown. Recent additional measurements and future ones giving excitation functions for resolved configurations and complementary Auger data will provide even more sensitive tests of collisional correlation theory. 15 refs., 3 figs., 1 tab.

Becker, R.L.

1986-01-01

385

Elsevier Science  

NSDL National Science Digital Library

Elsevier Science, the scientific communications branch of Reed Elsevier, started its official World-Wide Web and Gopher service which includes: the Elsevier Science Internet Catalogue of Journals and Books; information about - TULIP - The University Licensing Program, a research project Elsevier Science is performing with nine universities in the USA; and, the Proceedings of the WWW'94 Conference (May 25-27, 1994), organized by CERN, Geneva; a number of current awareness services on diverse areas of science.

1998-01-01

386

Dynamical analysis of highly excited molecular spectra  

SciTech Connect

The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

Kellman, M.E. [Univ. of Oregon, Eugene (United States)

1993-12-01

387

When inhibition not excitation synchronizes neural firing  

Microsoft Academic Search

Excitatory and inhibitory synaptic coupling can have counter-intuitive effects on the synchronization of neuronal firing. While it might appear that excitatory coupling would lead to synchronization, we show that frequently inhibition rather than excitation synchronizes firing. We study two identical neurons described by integrate-and-fire models, general phase-coupled models or the Hodgkin-Huxley model with mutual, non-instantaneous excitatory or inhibitory synapses between

CARL VAN VREESWIJK; L. F. Abbott; G. Bard Ermentrout

1994-01-01

388

HF excited instabilities in space plasmas  

Microsoft Academic Search

Radio waves delivering sufficiently strong electric field strengths to a plasma can excite parametric instabilities in the plasma for properly matched conditions. Technology had advanced by 1970 to the stage where this could be effected in the ionospheric plasma by ground-based installations. High-power HF transmitters, in the nominal 3-12 MHz range, deposited substantial energy in the ionospheric plasma, raising thermal

H. C. Carlson; L. M. Duncan

1977-01-01

389

Biochemical Brain Markers in Excited Delirium Deaths  

Microsoft Academic Search

\\u000a Over the past decade, increased attention has been paid to the sudden deaths of some highly agitated subjects held in police\\u000a custody, which were restrained or incapacitated by CEWs. Medical examiners often have extreme difficulty in identifying the\\u000a cause of death, but frequently drug intoxication is considered a contributing factor. The symptoms of excited delirium include\\u000a bizarre and\\/or aggressive behavior,

Deborah C. Mash

390

Control of self-excited induction generators  

Microsoft Academic Search

In this paper, experimental results on the self excitation of induction generators have been investigated to obtain a secure and stable power generation. A micro power simulator which consists of a small-scale synchronous generator (0.5 kW) and a squirrel cage induction generator (0.4 kW) controlled by a servomotor and an equivalent LC network of the transmission line is successfully used

F. Naito; K. Abe

2002-01-01

391

Alternating current-excited magnetoresistive sensor  

Microsoft Academic Search

Thin-film anisotropic magnetoresistors are superior to semiconductor magnetic field sensors. ac excitation of the sensor bridge reduced the noise level to 10 nT p-p. The offset reduction and sensor characteristic stabilization was achieved by periodical flipping by means of 100 mA\\/100 ?s current pulses into a 400 turns coil wound across the sensor perpendicular to the sensitive axis. The use

P. Ripka

1996-01-01

392

Excitation of fields in geoelectric experiments  

NASA Astrophysics Data System (ADS)

The paper discusses the premises and possibilities for expanding the experimental base of controlled-source geoelectrics. A nonstationary electric field (E-field, E-mode, and TM-field) and the means for its excitation are examined as a reserve. The appendix presents a compact description of the mathematical apparatus applicable to results of transient electromagnetic sounding with an arbitrary source on the basis of two methods that lead to the Fourier integral and (under certain constraints) Fourier series representations.

Mogilatov, V. S.; Potapov, V. V.

2007-05-01

393

Excitations of the nucleon with dynamical fermions  

SciTech Connect

We measure the spectrum of low-lying nucleon resonances using Bayesian fitting methods. We compare the masses obtained in the quenched approximation to those obtained with two flavours of dynamical fermions at a matched lattice spacing. At the pion masses employed in our simulations, we find that the mass of the first positive-parity nucleon excitation is always greater than that of the parity partner of the nucleon.

C.M. Maynard; D.G. Richards

2002-06-01

394

On the vertical excitation energy of cyclopentadiene  

NASA Astrophysics Data System (ADS)

The vertical excitation energy for the lowest valence ???* transition of cyclopentadiene is investigated. Using a combination of high-level theoretical methods and spectroscopic simulations, the vertical separation at the ground state geometry is estimated to be 5.43±0.05 eV. This value is intermediate between those calculated with coupled-cluster and multireference perturbation theory methods and is about 0.13 eV higher than the observed maximum in the absorption profile.

Bomble, Yannick J.; Sattelmeyer, Kurt W.; Stanton, John F.; Gauss, Jürgen

2004-09-01

395

Search for Excited Leptons at HERA  

E-print Network

Searches for excited electrons and neutrinos have been performed using the complete HERA I and II data samples collected by the H1 detector at $\\sqrt{s}=320$ GeV corresponding to an integrated luminosity of up to 435 pb$^{-1}$. In absence of a signal, the limits on the ratio of the coupling to the compositeness scale derived extend the excluded region to higher masses than has been possible in previous searches.

Thi Nguyet Trinh; for the H1 Collaboration

2007-07-26

396

Collisional excitation of interstellar methyl cyanide  

NASA Technical Reports Server (NTRS)

Theoretical calculations are used to determine the collisional excitation rates of methyl cyanide under interstellar molecular cloud conditions. The required Q(L,M) as a function of kinetic temperature were determined by averaging fixed energy IOS (infinite order sudden) results over appropriate Boltzmann distributions of collision energies. At a kinetic temperature of 40 K, rates within a K ladder were found to be accurate to generally better than about 30 percent.

Green, Sheldon

1986-01-01

397

Information resonance in a model excitable system  

NASA Astrophysics Data System (ADS)

We consider a simple mesoscopic model of an excitable thermochemical system for which the system temperature as a function of time has a form of irregular spikes. The interspike intervals are mapped onto elements of a formal alphabet. The time evolution of system temperature is represented by a string over this alphabet. We demonstrate that the entropy of such string reaches a minimum for the values of model parameters where the coherence resonance of interspike intervals is observed.

Gorecki, Jerzy; Gorecki, Adam; Lemarchand, Annie; Nowakowski, Bogdan

2013-06-01

398

Self-excitation of single nanomechanical pillars  

Microsoft Academic Search

Self-excitation is a mechanism that is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators (Nedic and Lipo 2000 IEEE\\/IAS Conf. Records (Rome, Italy) vol 1 pp 51–6), a good and widely visible example of which is the wind turbine farm (Muljadi et al 2005

Hyun S Kim; Hua Qin; Robert H Blick

2010-01-01

399

Self-excitation of single nanomechanical pillars  

Microsoft Academic Search

Self-excitation is a mechanism that is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators (Nedic and Lipo 2000 IEEE\\/IAS Conf. Records (Rome, Italy) vol 1 pp 51-6), a good and widely visible example of which is the wind turbine farm (Muljadi et al 2005

Hyun S. Kim; Hua Qin; Robert H. Blick

2010-01-01

400

Self Excitation of Nano-Mechanical Pillars  

Microsoft Academic Search

Self excitation is a mechanism which is ubiquitous for electromechanical\\u000apower devices such as electrical generators. This is conventionally achieved by\\u000amaking use of the magnetic field component in electrical generators [1], where\\u000aa good example are the overall visible wind farm turbines [2]. In other words,\\u000aa static force, like wind acting on the rotor blades, can generate a

Hyun S. Kim; Hua Qin; Robert H. Blick

2007-01-01

401

Sound Science  

ERIC Educational Resources Information Center

How can a teacher simultaneously teach science concepts through inquiry while helping students learn about the nature of science? After pondering this question in their own teaching, the authors developed a 5E learning cycle lesson (Bybee et al. 2006) that concurrently embeds opportunities for fourth-grade students to (a) learn a science concept,…

Sickel, Aaron J.; Lee, Michele H.; Pareja, Enrique M.

2010-01-01

402

Dramatic Science  

ERIC Educational Resources Information Center

The setting: the science classroom. The characters: you and your students. The scene: Your students acting out scientific discoveries, modeling a frog's life cycle, mimicking the transition from liquid to solid. This is "dramatic science", a teaching approach that uses acting techniques to explore and develop young children's ideas about science.…

McGregor, Debbie; Precious, Wendy

2010-01-01

403

Understanding Science  

NSDL National Science Digital Library

This page, from University of California Museum of Paleontology, features free, image-rich teaching resources that communicate what science is and how it works, with a focus on the process of science and its dynamic nature. The project is geared toward K-16 teacher preparation as well as broader public understanding of the nature of science.

Paleontology, University O.

404

Safer Science  

ERIC Educational Resources Information Center

This column provides best safety practices for the science classroom and laboratory. In this month's issue, pregnancy policy in the laboratory is discussed. One can't ignore the fact that student and faculty pregnancies--and the resulting potential hazards in the science laboratory--exist at the high school level. Science teachers need to be…

Roy, Ken

2011-01-01

405

14. POWERHOUSE INTERIOR, EXCITER No. 2 SHOWING GENERAL ELECTRIC INDUCTION ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. POWERHOUSE INTERIOR, EXCITER No. 2 SHOWING GENERAL ELECTRIC INDUCTION MOTOR IN SERIES BETWEEN PELTON-DOBLE IMPULSE WHEEL AND GENERAL ELECTRIC GENERATOR. VIEW TO EAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

406

Strong decays of excited baryons in Large Nc QCD  

SciTech Connect

We present the analysis of the strong decays widths of excited baryons in the framework of the 1/Nc expansion of QCD. These studies are performed up to order 1/Nc and include both positive and negative parity excited baryons.

Jose Goity; Norberto Scoccola

2007-02-01

407

6. POWERHOUSE INTERIOR SHOWING EXCITER No. 1. HANDCONTROLLED GATE VALVE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. POWERHOUSE INTERIOR SHOWING EXCITER No. 1. HAND-CONTROLLED GATE VALVE SHOWN ON NOZZLE TO PELTON-DOBLE IMPULSE WHEEL. VIEW TO NORTHEAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

408

12. POWERHOUSE INTERIOR SHOWING EXCITER No. 2 SMALL PELTONDOBLE IMPULSE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. POWERHOUSE INTERIOR SHOWING EXCITER No. 2 SMALL PELTON-DOBLE IMPULSE WHEEL, HAND-CONTROLLED GATE VALVE, AND NOZZLE. VIEW TO SOUTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

409

13. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC INDUCTION MOTOR NAMEPLATE. VIEW TO EAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

410

Shock Excitation in Interacting Galaxies: Mkn 266  

E-print Network

We present near infrared data on the luminous interacting system Mkn 266 (NGC 5256), comprising 2um continuum, and Br_gamma and 1-0S(1) emission line images, together with K-band spectra. We have fitted stellar templates to the continuum, allowing us to account for all the stellar features and hence detect even faint gas excitation emission lines, including 8 and 11 H_2 lines in the SW and NE nuclei respectively. Population diagrams for the excited H_2 molecules indicate that most of the 1-0S(1) in each of the nuclei has a thermal origin. We discuss this with reference to the observed morphologies, especially that of the 1-0S(1) line. In particular, the core of 1-0S(1) in the NE nucleus is more compact than the 2um continuum; while in the SW nucleus the 1-0S(1) is significantly offset by 500pc from the continuum (and other) emission. Lastly we address the issue of the region midway between the two nuclei, where previously a strong source of radio continuum has been observed. These results are set in the context of interacting galaxies where shock excited emission might be expected to occur as a direct consequence of the interaction.

R. Davies; M. Ward; H. Sugai

2000-01-19

411

DYNAMICAL ANALYSIS OF HIGHLY EXCITED MOLECULAR SPECTRA  

SciTech Connect

Spectra and internal dynamics of highly excited molecules are essential to understanding processes of fundamental importance for combustion, including intramolecular energy transfer and isomerization reactions. The goal of our program is to develop new theoretical tools to unravel information about intramolecular dynamics encoded in highly excited experimental spectra. We want to understand the formations of ''new vibrational modes'' when the ordinary normal modes picture breaks down in highly excited vibrations. We use bifurcation analysis of semiclassical versions of the effective Hamiltonians used by spectroscopists to fit complex experimental spectra. Specific molecular systems are of interest for their relevance to combustion and the availability of high-quality experimental data. Because of its immense importance in combustion, the isomerizing acetylene/vinylidene system has been the object of long-standing experimental and theoretical research. We have made significant progress in systematically understanding the bending dynamics of the acetylene system. We have begun to make progress on extending our methodology to the full bend-stretch vibrational degrees of freedom, including dynamics with multiple wells and above barrier motion, and time-dependent dynamics. For this, development of our previous methods using spectroscopic fitting Hamiltonians is needed, for example, for systems with multiple barriers.

Michael E. Kellman

2005-06-17

412

Excitation of a composite structure by collisions  

SciTech Connect

A simple model is employed to study the excitation of a composite structure by collisions. The composite structure is a diatomic ''molecule'' composed of two equal point masses joined by a Hooke's law spring of constant, k/sub 1/. This structure, in an unexcited state, makes a one-dimensional head-on collision with a fixed wall. The interaction with the wall is mediated by a second Hooke's law spring of constant, k/sub 2/. After rebounding from the wall the diatom may be in an excited state. The excitation energy is calculated as a function of the hardness of the wall. An eigenvalue problem is solved which yields an infinite number of ..beta..'s (..beta.. = k/sub 1//k/sub 2/) which leave the diatom unexcited. The phenomenon of ''double hitting'' : when a soft structure strikes a hard wall: is discussed. The maximum energy transfer into the internal mode is 23%. An air-track experiment is suggested to check the theoretical predictions.

Newby, N.D. Jr.

1984-08-01

413

Understanding highly excited states via parametric variations  

NASA Astrophysics Data System (ADS)

Highly excited vibrational states of an isolated molecule encode the vibrational energy flow pathways in the molecule. Recent studies have had spectacular success in understanding the nature of the excited states mainly due to the extensive studies of the classical phase space structures and their bifurcations. Such detailed classical-quantum correspondence studies are presently limited to two- or quasi-two-dimensional systems. One of the main reasons for such a constraint has to do with the problem of visualization of relevant objects like surface of sections and Wigner or Husimi distributions associated with an eigenstate. This necessitates various alternative techniques which are more algebraic than geometric in nature. In this work we introduce one such method based on parametric variation of the eigenvalues of a Hamiltonian. It is shown that the level velocities are correlated with the phase space nature of the corresponding eigenstates. A semiclassical expression for the level velocities of a single resonance Hamiltonian is derived which provides theoretical support for the correlation. We use the level velocities to dynamically assign the highly excited states of a model spectroscopic Hamiltonian in the mixed phase space regime. The effect of bifurcations on the level velocities is briefly discussed using a recently proposed spectroscopic Hamiltonian for the HCP molecule.

Semparithi, Aravindan; Charulatha, Venkataraman; Keshavamurthy, Srihari

2003-01-01

414

Experimental Overview of the Excited Baryon Program  

NASA Astrophysics Data System (ADS)

High-energy electrons and photons are a remarkably clean probe of hadronic matter, essentially providing a microscope for examining atomic nuclei and the strong nuclear force. For more than a decade, laboratories worldwide have accumulated data for such investigations, resulting in a number of surprising discoveries and contributing to our understanding of the nucleon, its underlying quark structure, and the dynamics of the strong interaction. One notable discovery has been the unexpected Q2 variation of the ratio of the proton elastic form-factors GEp/GMp, which suggests an important contribution from quark orbital angular momentum to the spin of the nucleon. Moreover, the spectrum of excited hadrons can serve as an excellent probe of Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Since nucleons are complex systems of confined quarks, they exhibit the characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within QCD. The current effort at facilities worldwide studying the systematics of hadron spectra is to utilize highly-polarized frozen-spin (butanol) and deuterium targets in combination with polarized photon beams. These are important steps toward complete experiments that allow us to unambiguously determine the scattering amplitude in the underlying reactions and to identify resonance contributions.

Crede, Volker

2011-05-01

415

Motional sideband excitation using rotating electric fields  

NASA Astrophysics Data System (ADS)

A form of motional sideband excitation is described in which a rotating dipole electric field is applied asymmetrically onto a Penning-type trap in the presence of a mechanism for cooling the axial motion of the trapped particles. In contrast to the traditional motional sideband excitation, which uses an oscillating electric field, the rotating field results in only one active sideband in each sense of rotation and so avoids accidental excitation of the other sideband making it applicable to Penning-type traps with a large degree of anharmonicity. Expressions are derived for the magnetron radius expansion and compression rates attainable, and approximations are made for the case of strong and weak drives. A comparison is made with data, taken using a two-stage positron accumulator presented by Isaac [C. A. Isaac, C. J. Baker, T. Mortensen, D. P. van der Werf, and M. Charlton, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.033201 107, 033201 (2011)], showing good agreement between the model and experiment.

Isaac, C. A.

2013-04-01

416

Magnetic excitation spectra in pyrochlore iridates  

NASA Astrophysics Data System (ADS)

Metal-insulator transitions in pyrochlore iridates (A2Ir2O7) are believed to occur due to subtle interplay of spin-orbit coupling, geometric frustration, and electron-electron interactions. In particular, the nature of magnetic ordering of iridium ions in the insulating phase is crucial for the understanding of several exotic phases recently proposed for these materials. We study the spectrum of magnetic excitations in the intermediate-coupling regime for the so-called all-in/all-out magnetic state in pyrochlore iridates with nonmagnetic A-site ions (A = Eu,Y). This state was found to be preferred in previous theoretical studies. We find that the effect of charge fluctuations on the magnetic excitations in the intermediate-coupling regime leads to a strong departure from the lowest-order spin-wave calculations based on spin models obtained in the strong-coupling limit. We discuss the characteristic features of the magnetic excitation spectrum that can lead to conclusive identification of the magnetic order in future resonant inelastic x-ray (or neutron) scattering experiments. This knowledge about the nature of magnetic order and its low-energy features may also provide useful information on the accompanying metal-insulator transition.

Lee, Eric Kin-Ho; Bhattacharjee, Subhro; Kim, Yong Baek

2013-06-01

417

Experimental Overview of the Excited Baryon Program  

SciTech Connect

High-energy electrons and photons are a remarkably clean probe of hadronic matter, essentially providing a microscope for examining atomic nuclei and the strong nuclear force. For more than a decade, laboratories worldwide have accumulated data for such investigations, resulting in a number of surprising discoveries and contributing to our understanding of the nucleon, its underlying quark structure, and the dynamics of the strong interaction. One notable discovery has been the unexpected Q{sup 2} variation of the ratio of the proton elastic form-factors G{sub E}{sup p}/G{sub M}{sup p}, which suggests an important contribution from quark orbital angular momentum to the spin of the nucleon. Moreover, the spectrum of excited hadrons can serve as an excellent probe of Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Since nucleons are complex systems of confined quarks, they exhibit the characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within QCD. The current effort at facilities worldwide studying the systematics of hadron spectra is to utilize highly-polarized frozen-spin (butanol) and deuterium targets in combination with polarized photon beams. These are important steps toward complete experiments that allow us to unambiguously determine the scattering amplitude in the underlying reactions and to identify resonance contributions.

Crede, Volker [Florida State University, Department of Physics, Tallahassee, FL 32306 (United States)

2011-05-23

418

RF excited laser with internally folded resonator  

SciTech Connect

This patent describes a transversely RF excited gas laser with an internally folded resonator. The transversely RF excited gas laser comprising: an elongated chamber of cross- sectional dimensions suitable for confining a laser gas discharge; a plurality of reflectors which form a stable folded laser resonator cavity of a compact geometry in order to efficiently extract laser power from the laser resonator cavity wherein there are at least two of the plurality of reflectors and at least one of the plurality of reflectors is concave; a laser gas which is disposed in the folded resonator cavity which reflect and guide light energy from the laser gas discharge within the elongated chamber; a pair of electrodes are transversely disposed on the elongated chamber and excite the laser gas; a pair of cooling electrodes are transversely disposed on the elongated chamber and electrically coupled to ground; and impedance- matching means for applying RF power to the pair of electrodes. The impedance matching means including three inductors with a center-tapped coil being adjusted so that the voltage potential at the center of the laser discharge between the pair of cooling electrodes is a virtual ground thereby preventing RF current from passing through the pair of grounded cooling electrodes in order to efficiently extract laser power from the laser resonator cavity.

Sutter, L.V.; Cameron, H.A.; Davison, M.R.

1990-01-02

419

Excitation energy transfer in the photosystem I  

SciTech Connect

Photosystem I is a multimeric pigment protein complex in plants, green alage and cyanobacteria that functions in series with Photosystem II to use light energy to oxidize water and reduce carbon dioxide. The Photosystem I core complex contains 96 chlorophyll a molecules and 22 carotenoids that are involved in light harvesting and electron transfer. In eucaryotes, PSI also has a peripheral light harvesting complex I (LHCI). The role of specific chlorophylls in excitation and electron transfer are still unresolved. In particular, the role of so-called bridging chlorophylls, located between the bulk antenna and the core electron transfer chain, in the transfer of excitation energy to the reaction center are unknown. During the past funding period, site directed mutagenesis has been used to create mutants that effect the physical properties of these key chlorophylls, and to explore how this alters the function of the photosystem. Studying these mutants using ultrafast absorption spectroscopy has led to a better understanding of the process by which excitation energy is transferred from the antenna chlorophylls to the electron transfer chain chlorophylls, and what the role of connecting chlorophylls and A_0 chlorophylls is in this process. We have also used these mutants to investigate whch of the central group of six chlorophylls are involved in the primary steps of charge separation and electron transfer.

Webber, Andrew N.

2012-09-25

420

Worms and Trees: An Exciting Adventure.  

ERIC Educational Resources Information Center

Outlines procedures for using silkworms in elementary science, mathematics, history, ecology, social studies, language arts, art, and physical education. Also focuses on the silkworm's use of the mulberry tree. (DDR)

El Harim, Jean Love

1997-01-01

421

The Forum: The Soft Shoe and Hard Sell of Science Teaching  

ERIC Educational Resources Information Center

Dispels the notion that exciting and imaginative science is the result of packaged curriculum materials or teaching methods. Instead, the necessity to follow students' inclinations and desires rather than rigid study guides is advocated. (CP)

Twaronite, Eugene A.

1978-01-01

422

ComputationalComputational ScienceScience  

E-print Network

ComputationalComputational ScienceScience KenKen HawickHawick k.a.k.a.hawickhawick@massey.ac.nz@massey.ac.nz Massey UniversityMassey University #12;Computational Science / eScienceComputational Science / eScience Computational Science concerns the application of computer science to physics, mathematics, chemistry, biology

Hawick, Ken

423

Searches for excited fermions in ep collisions at HERA  

Microsoft Academic Search

Searches in ep collisions for heavy excited fermions have been performed with the ZEUS detector at HERA. Excited states of electrons and quarks have been searched for in e+p collisions at a centre-of-mass energy of 300 GeV using an integrated luminosity of 47.7 pb?1. Excited electrons have been sought via the decays e??e?, e??eZ and e???W. Excited quarks have been sought via

S. Bhadra; C. D. Catterall; W. R. Frisken; M. Khakzad; S. Magill; B. Musgrave; A. Pellegrino; J. Repond; R. Yoshida; M. C. K. Mattingly; P. Antonioli; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; G. Cara Romeo; L. Cifarelli; F. Cindolo; A. Contin; M. Corradi; S. de Pasquale; P. Giusti; G. Iacobucci; G. Levi; A. Margotti; T. Massam; R. Nania; F. Palmonari; A. Pesci; G. Sartorelli; A. Zichichi; G. Aghuzumtsyan; I. Brock; S. Goers; H. Hartmann; E. Hilger; P. Irrgang; H.-P. Jakob; A. Kappes; U. F. Katz; R. Kerger; O. Kind; E. Paul; J. Rautenberg; H. Schnurbusch; A. Stifutkin; J. Tandler; K. C. Voss; A. Weber; H. Wieber; D. S. Bailey; N. H. Brook; J. E. Cole; B. Foster; G. P. Heath; H. F. Heath; S. Robins; E. Rodrigues; J. Scott; R. J. Tapper; M. Wing; M. Capua; A. Mastroberardino; M. Schioppa; G. Susinno; H. Y. Jeoung; J. Y. Kim; J. H. Lee; I. T. Lim; K. J. Ma; M. Y. Pac; A. Caldwell; M. Helbich; X. Liu; B. Mellado; S. Paganis; W. B. Schmidke; F. Sciulli; J. Chwastowski; A. Eskreys; J. Figiel; K. Klimek; K. Olkiewicz; M. B. Przybycien; P. Stopa; L. Zawiejski; B. Bednarek; I. Grabowska-Bold; K. Jelen; D. Kisielewska; A. M. Kowal; M. Kowal; T. Kowalski; B. Mindur; E. Rulikowska-Zarebska; L. Suszycki; D. Szuba; J. Szuba; A. Kotanski; L. A. T. Bauerdick; U. Behrens; K. Borras; V. Chiochia; J. Crittenden; D. Dannheim; K. Desler; G. Drews; A. Fox-Murphy; U. Fricke; A. Geiser; F. Goebel; P. Göttlicher; R. Graciani; T. Haas; W. Hain; G. F. Hartner; K. Hebbel; S. Hillert; U. Kötz; H. Kowalski; H. Labes; B. Löhr; R. Mankel; J. Martens; M. Martínez; M. Milite; M. Moritz; D. Notz; M. C. Petrucci; A. Polini; U. Schneekloth; F. Selonke; S. Stonjek; B. Surrow; J. J. Whitmore; R. Wichmann; G. Wolf; C. Youngman; W. Zeuner; C. Coldewey; A. Lopez-Duran Viani; A. Meyer; S. Schlenstedt; G. Barbagli; E. Gallo; P. G. Pelfer; A. Bamberger; A. Benen; N. Coppola; P. Markun; H. Raach; S. Wölfle; M. Bell; P. J. Bussey; A. T. Doyle; C. Glasman; S. W. Lee; A. Lupi; G. J. McCance; D. H. Saxon; I. O. Skillicorn; B. Bodmann; N. Gendner; U. Holm; H. Salehi; K. Wick; A. Yildirim; A. Ziegler; T. Carli; A. Garfagnini; I. Gialas; E. Lohrmann; C. Foudas; R. Gonçalo; K. R. Long; F. Metlica; D. B. Miller; A. D. Tapper; R. Walker; P. Cloth; D. Filges; M. Kuze; K. Nagano; K. Tokushuku; S. Yamada; Y. Yamazaki; A. N. Barakbaev; E. G. Boos; N. S. Pokrovskiy; B. O. Zhautykov; S. H. Ahn; S. B. Lee; S. K. Park; H. Lim; D. Son; F. Barreiro; G. García; O. González; L. Labarga; J. del Peso; I. Redondo; J. Terrón; M. Vázquez; M. Barbi; A. Bertolin; F. Corriveau; A. Ochs; S. Padhi; D. G. Stairs; M. St-Laurent; T. Tsurugai; A. Antonov; V. Bashkirov; P. Danilov; B. A. Dolgoshein; D. Gladkov; V. Sosnovtsev; S. Suchkov; R. K. Dementiev; P. F. Ermolov; Yu. A. Golubkov; I. I. Katkov; L. A. Khein; N. A. Korotkova; I. A. Korzhavina; V. A. Kuzmin; B. B. Levchenko; O. Yu. Lukina; A. S. Proskuryakov; L. M. Shcheglova; A. N. Solomin; N. N. Vlasov; S. A. Zotkin; C. Bokel; J. Engelen; S. Grijpink; E. Koffeman; P. Kooijman; E. Maddox; S. Schagen; E. Tassi; H. Tiecke; N. Tuning; J. J. Velthuis; L. Wiggers; E. de Wolf; N. Brümmer; B. Bylsma; L. S. Durkin; J. Gilmore; C. M. Ginsburg; C. L. Kim; T. Y. Ling; S. Boogert; A. M. Cooper-Sarkar; R. C. E. Devenish; J. Ferrando; J. Große-Knetter; T. Matsushita; M. Rigby; O. Ruske; M. R. Sutton; R. Walczak; R. Brugnera; R. Carlin; F. dal Corso; S. Dusini; S. Limentani; A. Longhin; A. Parenti; M. Posocco; L. Stanco; M. Turcato; L. Adamczyk; L. Iannotti; B. Y. Oh; P. R. B. Saull; W. S. Toothacker; Y. Iga; G. D'Agostini; G. Marini; A. Nigro; C. Cormack; J. C. Hart; N. A. McCubbin; C. Heusch; I. H. Park; N. Pavel; H. Abramowicz; S. Dagan; A. Gabareen; S. Kananov; A. Kreisel; A. Levy; T. Abe; T. Fusayasu; T. Kohno; K. Umemori; T. Yamashita; R. Hamatsu; T. Hirose; M. Inuzuka; S. Kitamura; K. Matsuzawa; T. Nishimura; M. Arneodo; N. Cartiglia; R. Cirio; M. Costa; M. I. Ferrero; S. Maselli; V. Monaco; C. Peroni; M. Ruspa; R. Sacchi; A. Solano; A. Staiano; D. C. Bailey; C.-P. Fagerstroem; R. Galea; T. Koop; G. M. Levman; J. F. Martin; A. Mirea; A. Sabetfakhri; J. M. Butterworth; C. Gwenlan; R. Hall-Wilton; M. E. Hayes; E. A. Heaphy; T. W. Jones; M. S. Lightwood; B. J. West; J. Ciborowski; R. Ciesielski; G. Grzelak; R. J. Nowak; J. M. Pawlak; B. Smalska; T. Tymieniecka; A. Ukleja; J. Ukleja; J. A. Zakrzewski; A. F. Zarnecki; M. Adamus; P. Plucinski; J. Sztuk; Y. Eisenberg; L. K. Gladilin; D. Hochman; U. Karshon; J. Breitweg; D. Chapin; R. Cross; D. Kçira; S. Lammers; D. D. Reeder; A. A. Savin; W. H. Smith; A. Deshpande; S. Dhawan; V. W. Hughes; P. B. Straub; S. Menary

2002-01-01

424

Fantastic Physics: Developing an Early Interest in Science. A Preschool Science Curriculum. 3 Year Old Curriculum.  

ERIC Educational Resources Information Center

Using hands-on activities and the "Plan, Do, Review" approach, this physics curriculum for 3-year-old children is designed to develop an early interest in and enthusiasm for science and to excite children about learning in general. The curriculum is designed to be implemented biweekly in preschool or child care programs but may also be presented…

Summer, Gail L.; Giovannini, Kathleen

425

Science and Science Fiction Films.  

ERIC Educational Resources Information Center

Describes an undergraduate physics course for nonscience majors which combines physics with science fiction films. Includes course format, sample module on the concept of momentum, and an appendix with a listing of science fiction films used in this course. (DS)

Dubeck, Leroy W.

1981-01-01

426

How a Trip to the Freezer Can Help Children Learn Science  

ERIC Educational Resources Information Center

There are lots of exciting ways for children to learn science. Going on a journey is one of them. However, when going to distant places is not possible, a virtual journey may be the next best option. Ricky, one of the authors' puppets, helps children to make virtual journeys, and this can create an exciting context for them to raise questions and…

Keogh, Brenda; Naylor, Stuart

2011-01-01

427

Shenandoah elementary science enrichment program  

SciTech Connect

Shenandoah Elementary School is a rural educational facility located in the farmlands of Indiana. The Elementary Science Enrichment Program was established to create a learning atmosphere that encourages scientific thinking and problem-solving. Its inception was founded on the belief that the concepts and process skills inherent in the teaching of science are critical to the early intellectual development of elementary students. The program was established through speaking engagements at the local and state level which resulted in the necessary support to insure its continuation. All students in grades K-5 meet for weekly science activities in our elementary lab to investigate many exciting curricular areas including planaria regeneration, star life cycles, and acid rain telecommunications. This allows for in-depth exploration of the science process skills which culminate in a variety of products including student portfolios, hands-on assessments, simulations and global data communications. These activities are extended through family science and the modeling of science instructional techniques for classroom educators.

Garrett, P. [Shenandoah Elementary School, Middletown, IN (United States)

1994-12-31

428

Meteorological excitations of polar motion for an Earth model with frequency-dependent responses  

NASA Astrophysics Data System (ADS)

Polar motion excitation involves the mass redistributions and motions of the Earth system relative to the mantle, as well as the frequency-dependent rheology of the Earth, where the latter has recently been modeled in the form of complex and frequency-dependent Love numbers and polar motion excitation transfer functions. At seasonal and intra-seasonal time scales, polar motions are dominated by angular momentum fluctuations due to mass redistributions and relative motions in the atmosphere, oceans, and continental water, snow and ice. In this study, we compare the geophysical excitations derived from various global atmospheric, oceanic and hydrological models (NCEP, ECCO, ERA40, ERAinterim and ECMWF operational products), and construct two model sets LDC1 and LDC2 by combining the above models with a least difference method, which selects FFT coefficients of the above data series closest to those of the geodetic excitation at each frequency to build a new series. Comparisons between the geodetic excitation (derived from the polar motion series IERS EOP 08 C04) and the geophysical excitations (based on those meteorological models) imply that the atmospheric models are the most reliable while the hydrological ones suffer from significant uncertainties; that the ERAinterim is, in general, the best model set among the original ones, but the combined models LDC1 and LDC2 are much better than ERAinterim; and that applying the frequency-dependent transfer functions to LDC1 and LDC2 improves their agreements with the geodetic excitation. Thus, we conclude that the combined models LDC1 and LDC2 are reliable, and the complex and frequency-dependent Love numbers and polar motion excitation transfer functions are well modeled. This study is supported in parts by the National 973 Project of China (No. 2013CB733301 and 2013CB733305), the National Natural Science Foundation of China (No. 41174011, 41128003 and 11073044), and the Open Fund of the State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, CAS (No. SKLGED2013-2-3-E).

Chen, Wei; Ray, Jim; Li, JianCheng; Shen, WenBin; Huang, ChengLi

2014-05-01

429

Ultrafast excited state dynamics of tris-  

NASA Astrophysics Data System (ADS)

Time resolved anisotropy measurements and time dependent transient absorption measurements are used to study the evolution of the photoexcited Franck-Condon state to the formation of the long-lived triplet metal-to-ligand charge-transfer (3MLCT) state in tris- (2,2'-bipyridine) ruthenium(II). [Ru(bpy)3]2+ represents a large class of inorganic compounds with interesting and potentially applicable photophysical properties. These compounds have generated much interest in the inorganic chemistry community because their photophysical properties are easily manipulated by synthetic chemistry methods. However, little remains known about the processes which govern the evolution from initial photoexcitation to the formation of the long-lived excited state. Metal to ligand charge transfer, when used to describe inorganic compounds, is a description of how the compound reacts to the absorption of light. Typically, these inorganic compounds are made of a transition metal with organic ligands, consisting of carbon, nitrogen and oxygen, coordinated in a highly symmetrical manner to the metal center. The highest occupied molecular orbitals (HOMO) in these compounds are isoenergetic with the frontier atomic orbitals of the metal and are localized to the metal center. The lowest unoccupied molecular orbitals (LUMO) are isoenergetic with the coordinating ligand orbitals and are localized to the ligands. Upon absorption of light in which an electron is promoted from the HOMO to the LUMO, the electron is excited from the metal to the ligands. Time dependent transient absorption measurements resolve the evolution of the initially excited state to the formation of the 3MLCT state. These measurements also reveal ultrafast dynamics which are characterized as intramolecular in nature and are associated with non-radiative relaxation processes. Symmetry argues the excited state should be delocalized among the bipyridine ligands. Rapid, solvent dependent depolarization of femtosecond anisotropy measurements indicate a change in symmetry of the excited state from a doubly degenerate delocalized state to a singly degenerate localized state. The anisotropy measurements also reveal that localization is facilitated through interactions with the solvent environment. Two distinct processes have been resolved in the evolution of the [Ru(bpy) 3]2+ Franck-Condon state to the formation of the 3MLCT state. Charge localization and ultrafast dynamics associated with non-radiative relaxation pathways are distinguished by their susceptibility to intermolecular interactions. These experiments represent the first measurements resolving these processes in the [Ru(bpy)3]2+ metal to ligand charge transfer complex.

Yeh, Alvin Tien-Wei

430

Magneto-roton excitation in a holographic quantum Hall fluid  

E-print Network

We compute the neutral bosonic excitation spectra of the holographic quantum Hall fluid described by the D3-D7' system. We find that the system is stable, gapped, and, in a range of parameters, exhibits a spectrum of low-lying excitations very similar to that of a quantum Hall fluid, including a magneto-roton excitation.

Niko Jokela; Gilad Lifschytz; Matthew Lippert

2010-12-06

431

Full expandable model of parallel self-excited induction generators  

E-print Network

Full expandable model of parallel self-excited induction generators F.A. Farret, B. Palle and M.G. Sim*oes Abstract: Self-excited induction generators (SEIG) offer many advantages as variable, the study of self-excited induction generators has regained importance, as they are particularly suitable

Simões, Marcelo Godoy

432

Steady-state analysis of Self Excited Induction Generator  

Microsoft Academic Search

Ab stract- This paper deals with an approach for the steady state analysis of Self Excited Induction Generator (SEIG). When an induction generator is used in an isolate operation, it operates in self-excitation made. Therefore the advanced knowledge of the maximum excitation capacitor value is required. To find this capacitor value two non-linear equations have to be solved. Different numerical

N. Mekkaoui; M.-S. Nait-Said; S. Drid

2011-01-01

433

Controlled excitation of a cold turbulent swirling free jet  

Microsoft Academic Search

Experimental results from acoustic excitation of a cold free turbulent jet with and without swirl are presented. A flow with a swirl number of 0.35 (i.e., moderate swirl) is excited internally by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that

R. Taghavi; E. J. Rice; S. Farokhi

1987-01-01

434

Self-trapped excitations in condensed matter physics  

Microsoft Academic Search

The authors discuss a general formulation for self-trapped excitations in condensed matter physics. Previously known aspects include lattice polarons, spin polarons, bubblons, etc. New aspects involve collective excitation self-trapping; solidons in liquid He have been suggested as the correct description for rotons. They emphasise the difference of self-trapped excitations with order parameter fluctuations.

M. Heritier; P. Lederer; G. Montambaux

1980-01-01

435

RF Pulse Design for Parallel Excitation in Magnetic Resonance Imaging  

E-print Network

Associated with Parallel Excitation .................................... 24 4. VARIABLE-DENSITY TRAJECTORY DESIGN FOR PARALLEL EXCITATION ................................................................................. 28 4.1 Spiral Design... ................................................................................................... 52 5. RF PULSE DESIGN INCORPORATING TISSUE DIELECTRIC PROPERTIES IN PARALLEL EXCITATION ................................................. 55 5.1 Joint RF Pulse and K-space Trajectory Adjustment ................................... 56...

Liu, Yinan

2012-07-16

436

Excitation mapping with the organic cation AGB 2+  

Microsoft Academic Search

Excitation mapping is a method of visualizing the signaling history of neurons with permeant organic cations. It is compatible with high-resolution imaging, allowing concurrent visualization of all neuronal classes and their glutamate-gated excitation histories. Excitation mapping documents the stability and precision of neuronal signaling within a given neuronal class, arguing that single unit electrophysiological sampling accurately reflects neuronal diversity. We

Robert E. Marc; Michael Kalloniatis; Bryan W. Jones

2005-01-01

437

Vortex phase-jitter in acoustically excited bluff body flames  

E-print Network

excitation on bluff body stabilized flames, specifically on the flow field characteristics. The Kelvin", manifested as cycle-to-cycle variation in flame and vorticity field at the same excitation phase. PhaseVortex phase-jitter in acoustically excited bluff body flames Santosh J. Shanbhogue, Michael

Lieuwen, Timothy C.

438

Dynamic Simulation of Powerformer Under Loss of Excitation  

Microsoft Academic Search

Powerformer is a kind of new high-voltage generator. The simulation method of dynamic simulation analysis of Powerformer under loss of excitation base on MATLAB\\/simulink is proposed. Simulation model of exciting windings open circuit based on simulink is built, and simulation result is analyzed. The changing regular pattern of exciting electric current, stator current, stator terminal voltage, active power and reactive

Lv Yanling; Ge Baojun; Li Cuicui; Zhang Zhiqiang

2009-01-01

439

Alinement and Modeling of Hanford Excitation Control for System Damping  

Microsoft Academic Search

The alinement of speed excitation supplementary control for each of the two Hanford 430 MW nuclear steam turbine-generator units was readily accomplished through field testing. Off-line frequency response tests of the supplementary control units, voltage regulators and exciters and frequency and step response test of the excitation system provided data used to develop a dynamic simulation model of the Hanford

Edward Warchol; Ferber Schleif; William Gish; John Church

1971-01-01

440

Master of Science in Applied Science Education  

E-print Network

Master of Science in Applied Science Education Student Handbook Division of Teacher Education................................................................................. 4 Program Requirements ­ Applied Science & Mathematics Track....... 4 Program Requirements ­ Earth Welcome to Michigan Tech University's Master of Science Program in Applied Science Education! Department

441

Decoherence dynamics of coherent electronic excited states in the photosynthetic purple bacterium Rhodobacter sphaeroides  

NASA Astrophysics Data System (ADS)

In this paper, we present a theoretical description to the quantum coherence and decoherence phenomena of energy transfer in photosynthesis observed in a recent experiment [Science 316, 1462 (2007)]. As a successive two-color laser pulses with selected frequencies cast on a sample of the photosynthetic purple bacterium Rb. sphaeroides two resonant excitations of electrons in chromophores can be generated. However, this effective two-level subsystem will interact with its protein environment and decoherence is inevitable. We describe this subsystem coupled with its environment as a dynamical spin-boson model. The non-Markovian decoherence dynamics is described using a quasiadiabatic propagator path integral (QUAPI) approach. With the photon-induced effective time-dependent level splitting energy and level flip coupling coefficient between the two excited states and the environment-induced non-Markovian decoherence dynamics, our theoretical result is in good agreement with the experimental data.

Liang, Xian-Ting; Zhang, Wei-Min; Zhuo, Yi-Zhong

2010-01-01

442

Crossing borders: High school science teachers learning to teach the specialized language of science  

NASA Astrophysics Data System (ADS)

The highly specialized language of science is both challenging and alienating to adolescent readers. This study investigated how secondary science teachers learn to teach the specialized language of science in their classrooms. Three research questions guided this study: (a) what do science teachers know about teaching reading in science? (b) what understanding about the unique language demands of science reading do they construct through professional development? and (c) how do they integrate what they have learned about these specialized features of science language into their teaching practices? This study investigated the experience of seven secondary science teachers as they participated in a professional development program designed to teach them about the specialized language of science. Data sources included participant interviews, audio-taped professional development sessions, field notes from classroom observations, and a prior knowledge survey. Results from this study suggest that science teachers (a) were excited to learn about disciplinary reading practices, (b) developed an emergent awareness of the specialized features of science language and the various genres of science writing, and (c) recognized that the challenges of science reading goes beyond vocabulary. These teachers' efforts to understand and address the language of science in their teaching practices were undermined by their lack of basic knowledge of grammar, availability of time and resources, their prior knowledge and experiences, existing curriculum, and school structure. This study contributes to our understanding of how secondary science teachers learn about disciplinary literacy and apply that knowledge in their classroom instruction. It has important implications for literacy educators and science educators who are interested in using language and literacy practices in the service of science teaching and learning. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Patrick, Jennifer Drake

443

131Cognitive Science COGNITIVE SCIENCE  

E-print Network

courses: Cognitive Science 110, 395, 403, 473; Computer Science 111, 211; Philosophy 106, 313; Psychology of Cognitive Sci- ence: Philosophy 205, 255, 305 (Psychology 305), 312; Sociology 222 (Classics 222) c. Experimental Cognitive Science: Psychology 207, 251, 252, 254, 255 d. CognitiveNeuropsychology:Neuroscience120

Marsh, David

444

Select Activities in the Regional Collaborative for Excellence in Science Teaching  

NASA Astrophysics Data System (ADS)

The Regional Collaborative for Excellence in Science Teaching employs many avenues of approach to engage teachers and students in science. A group of ``milestone'' discoveries is used to show science teachers how science is driven by new and exciting principles, which look mysterious initially, but lead to good understanding when the underlying principle for the discovery is found. An exciting program for prospective college bound students was initiated in the fall of 2009 supported by a grant from the President's office at UNT. The results of some of these activities will be presented.

Roberts, Jim

2010-03-01

445

Excited state dynamics of liquid water: Insight from the dissociation reaction following two-photon excitation  

E-print Network

We use transient absorption spectroscopy to monitor the ionization and dissociation products following two-photon excitation of pure liquid water. The two decay mechanisms occur with similar yield for an excitation energy of 9.3 eV, whereas the major channel at 8.3 eV is dissociation. The geminate recombination kinetics of the H and OH fragments, which can be followed in the transient absorption probed at 267 nm, provide a window on the dissociation dynamics at the lower excitation energy. Modeling the OH geminate recombination indicates that the dissociating H atoms have enough kinetic energy to escape the solvent cage and one or two additional solvent shells. The average initial separation of H and OH fragments is 0.7+-0.2 nm. Our observation suggests that the hydrogen bonding environment does not prevent direct dissociation of an O-H bond in the excited state. We discuss the implications of our measurement for the excited state dynamics of liquid water and explore the role of those dynamics in the ionizati...

Elles, C G; Crowell, R A; Shkrob, I A; Bradforth, Stephen E.; Crowell, Robert A.; Elles, Christopher G.; Shkrob, Ilya A.

2007-01-01

446

Excitation Spectra and Brightness Optimization of Two-Photon Excited Probes  

PubMed Central

Two-photon probe excitation data are commonly presented as absorption cross section or molecular brightness (the detected fluorescence rate per molecule). We report two-photon molecular brightness spectra for a diverse set of organic and genetically encoded probes with an automated spectroscopic system based on fluorescence correlation spectroscopy. The two-photon action cross section can be extracted from molecular brightness measurements at low excitation intensities, while peak molecular brightness (the maximum molecular brightness with increasing excitation intensity) is measured at higher intensities at which probe photophysical effects become significant. The spectral shape of these two parameters was similar across all dye families tested. Peak molecular brightness spectra, which can be obtained rapidly and with reduced experimental complexity, can thus serve as a first-order approximation to cross-section spectra in determining optimal wavelengths for two-photon excitation, while providing additional information pertaining to probe photostability. The data shown should assist in probe choice and experimental design for multiphoton microscopy studies. Further, we show that, by the addition of a passive pulse splitter, nonlinear bleaching can be reduced—resulting in an enhancement of the fluorescence signal in fluorescence correlation spectroscopy by a factor of two. This increase in fluorescence signal, together with the observed resemblance of action cross section and peak brightness spectra, suggests higher-order photobleaching pathways for two-photon excitation. PMID:22385865

Mutze, Jorg; Iyer, Vijay; Macklin, John J.; Colonell, Jennifer; Karsh, Bill; Petrasek, Zdenek; Schwille, Petra; Looger, Loren L.; Lavis, Luke D.; Harris, Timothy D.

2012-01-01

447

The photodissociation and reaction dynamics of vibrationally excited molecules  

SciTech Connect

This research determines the nature of highly vibrationally excited molecules, their unimolecular reactions, and their photodissociation dynamics. The goal is to characterize vibrationally excited molecules and to exploit that understanding to discover and control their chemical pathways. Most recently the author has used a combination of vibrational overtone excitation and laser induced fluorescence both to characterize vibrationally excited molecules and to study their photodissociation dynamics. The author has also begun laser induced grating spectroscopy experiments designed to obtain the electronic absorption spectra of highly vibrationally excited molecules.

Crim, F.F. [Univ. of Wisconsin, Madison (United States)

1993-12-01

448

Ultra-short strong excitation of two-level systems  

NASA Astrophysics Data System (ADS)

We present a model describing the use of ultra-short strong pulses to control the population of the excited level of a two-level quantum system. In particular, we study an off-resonance excitation with a few cycles pulse which presents a smooth phase jump i.e. a change of the pulse's phase which is not step-like, but happens over a finite time interval. A numerical solution is given for the time-dependent probability amplitude of the excited level. The control of the excited level's population is obtained acting on the shape of the phase transient, and other parameters of the excitation pulse.

Jha, Pankaj K.; Eleuch, Hichem; Grazioso, Fabio

2014-11-01

449

Standoff alpha radiation detection via excited state absorption of air  

SciTech Connect

A standoff alpha radiation detection technique based on the physical mechanism of excited state absorption of air molecules was explored and is presented in this paper. Instead of directly detecting the radiation via measuring the intensity of radiation induced air fluorescence, the radiation is detected via the excited state absorption of alpha radiation excited/ionized air molecules. Both theoretical analyses and experimental verifications were conducted. The experimental results confirmed that the radiation could be detected via excited state absorption of radiation excited/ionized air molecules at a 10 m standoff distance, which was consistent with the theoretical analyses.

Yao, Jimmy; Yin, Stuart Shizhuo [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Brenizer, Jack [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Hui, Rongqing [Department of Electrical Engineering and Computer Science, The University of Kansas, Lawrence, Kansas 66045 (United States)] [Department of Electrical Engineering and Computer Science, The University of Kansas, Lawrence, Kansas 66045 (United States)

2013-06-24

450

Collisional Excitation of Automotive Fuel Components (ethanol and Isooctane)  

NASA Astrophysics Data System (ADS)

It is possible to excite fuel components indirectly via a 10.6 um CO2 laser. A 9% solution of isopropanol in ethanol was used, as it has a strong absorption cross section at 10.6 um. CO2 laser excitation of pure ethanol caused little or no change in absorption in the C-H stretch region. However, the ethanol/isopropanol mixture did show a response proportional to laser excitation. Further studies indicate that excitation of isooctane/isopropanol mixture is also possible via collisional energy transfer between the laser excited isopropanol and isooctane.

Cobb, Rachelle H.; White, Allen R.; Devasher, Rebecca B.

2009-06-01

451

CLINICAL & TRANSLATIONAL SCIENCE CENTER  

E-print Network

UC DAVIS CLINICAL & TRANSLATIONAL SCIENCE CENTER CLINICAL & TRANSLATIONAL SCIENCE CENTER and Translational Science CenterClinical and Translational Science Center June 24, 2011June 24, 2011 #12;UC DAVIS CLINICAL & TRANSLATIONAL SCIENCE CENTER UC DAVIS CLINICAL & TRANSLATIONAL SCIENCE CENTER Goals

Carmichael, Owen

452

ENVIRONMENTAL SCIENCE AND  

E-print Network

ENVIRONMENTAL SCIENCE AND MANAGEMENT www.esr.pdx.edu Undergraduate Program: Environmental Science an emphasis on natural sciences and mathematics (Environmental Science) or emphasis on policy, geography and social sciences (Environmental Studies). Undergraduate Degrees Offered: Environmental Science Bachelor

453

Chatter suppression by parametric excitation: Model and experiments  

NASA Astrophysics Data System (ADS)

Chatter vibration leads to challenges in precise machining due to its harmful effect on productivity and surface quality. In this study, a chatter suppression method based on parametric excitation was developed. The effect of parametric excitation on self-excited vibration was investigated based on a model of a van der Pol-Mathieu-Duffing oscillator with a time delay. It reveals that there can be a zero solution for the oscillator under the effect of parametric excitation, while it is impossible to have a stable zero equation without parametric excitation. The stability of a parametrically excited vibration system regarding the regenerative effect in the cutting processes was studied by the averaging method. The stability analysis shows that parametric excitation with an appropriate frequency and large amplitude has a chatter suppression effect no matter whether the waveform is a sinusoidal wave, square wave or triangular wave. To validate the effect of parametric excitation for chatter suppression, experiments were conducted based on a magnetorheological (MR) fluid-controlled boring bar, which can generate high-frequency parametric excitation based on the quick response of the MR fluid. Cutting experiments with an excitation current of different waveforms and diverse frequencies show that chatter can be significantly suppressed by the effect of parametric excitation.

Yao, Zhehe; Mei, Deqing; Chen, Zichen

2011-06-01

454

Molecular Hydrogen Excitation in Ultraluminous Infrared Galaxies  

E-print Network

We report medium resolution VLT ISAAC K-band spectroscopy of the nuclei of seven ultraluminous infrared galaxies. After accounting for stellar absorption features, we have detected several molecular hydrogen (H_2) v=1-0, 2-1, and 3-2 vibrational emission lines, as well as the HI Br\\gamma and HeI 2^1P-2^1S recombination lines. The relative H_2 line intensities show little variation between the objects, suggesting that the H_2 excitation mechanisms in the nuclei are similar in all the objects. The 1-0 emissions appear thermalised at temperatures T\\sim1000K. However, the 2-1 and 3-2 emissions show evidence of being radiatively excited by far-ultraviolet (FUV) photons, suggesting that the H_2 excitation in the ULIRGs may arise in dense photon dominated regions (PDRs). We show that the line ratios in the nuclei are consistent with PDRs with cloud densities between 10^4 to 10^5cm^{-3}, exposed to far ultraviolet (FUV) radiation fields at least 10^3 times more intense than the ambient FUV intensity in the local interstellar medium. We have constructed starburst models for the ULIRGs based on their H_2 properties, as well as on the intensities of the recombination lines. Our models provide a consistent picture of young 1-5Myr star clusters surrounded by relatively dense PDRs which are irradiated by intense FUV fluxes. Comparison to the inner few hundred parsecs of the Milky Way indicates that the star formation efficiency in ULIRGs is 10--100 times higher than in the Galactic Center.

R. I. Davies; A. Sternberg; M. Lehnert; L. E. Tacconi-Garman

2003-07-23

455

Internal gravity wave excitation by turbulent convection  

NASA Astrophysics Data System (ADS)

We calculate the flux of internal gravity waves (IGWs) generated by turbulent convection in stars. We solve for the IGW eigenfunctions analytically near the radiative-convective interface in a local, Boussinesq and Cartesian domain. We consider both discontinuous and smooth transitions between the radiative and convective regions and derive Green's functions to solve for the IGWs in the radiative region. We find that if the radiative-convective transition is smooth, the IGW flux depends on the exact form of the buoyancy frequency near the interface. IGW excitation is most efficient for very smooth interfaces, which gives an upper bound on the IGW flux of ˜Fconv(d/H), where Fconv is the flux carried by the convective motions, d is the width of the transition region and H is the pressure scale height. This can be much larger than the standard result in the literature for a discontinuous radiative-convective transition, which gives a wave flux {˜ } F_conv {M}, where {M} is the convective Mach number. However, in the smooth transition case, the most efficiently excited perturbations will break in the radiative zone. The flux of IGWs which do not break and are able to propagate in the radiative region is at most {˜ } F_conv {M}^{5/8} (d/H)^{3/8}, larger than the discontinuous transition result by ({M}H/d)^{-3/8}. The transition region in the Sun is smooth for the energy-bearing waves; as a result, we predict that the IGW flux is a few to five times larger than previous estimates. We discuss the implications of our results for several astrophysical applications, including IGW-driven mass loss and the detectability of convectively excited IGWs in main-sequence stars.

Lecoanet, D.; Quataert, E.

2013-04-01

456

Vibrationally Excited H2 In Triton's Thermosphere  

NASA Astrophysics Data System (ADS)

We explore the possible impact that H2 vibrational excitation (expressed by an effec- tive vibrational temperature, Tv) might have on the ionospheric structure of Triton. Although our approach assumes that individual vibrational levels are in collisional equilibrium, it provides a useful way to represent the H2(v) distribution in Triton's thermosphere that allows us to assess the opening of nominally endothermic ion- neutral reaction channels. Some recent models of Triton have identified C+ as the main thermospheric ion, ignoring reaction with H2 as a loss mechanism since it is en- dothermic. However, the reaction of C+ with H2(v) becomes exothermic for the levels with v > 1. These vibrational levels may be populated by electron impact excitation and solar-induced resonance fluorescence of Lyman and Werner bands of H2. By including H2 vibrational excitation in our modified version of 1-D chemical dif- fusive model, together with a model of atmospheric temperatures and composition inferred from the Voyager-2 UVS solar occultation, we show that an ionosphere of mostly C+ or N+ ions is significantly modified for Tv exceeding 500 K. For a model with Tv of 2000 K and an extra ionization source of magnetospheric origin (equivalent to that estimated by Majeed et al. GRL, vol. 17, 1721, 1990)) an excellent agreement is obtained between the measured and calculated electron density profiles. N+ is the main ion at and above the ionospheric peak. For the same model, the calculated den- sities of atomic nitrogen at two altitudes (200 and 400 km) are also in good agreement with measured densities. Further details of the model and related results will be dis- cussed.

Majeed, T.; McConnell, J. C.; Gladstone, G. R.; Link, R.

457

Modeling short-pulse laser excitation of dielectric materials  

NASA Astrophysics Data System (ADS)

A theoretical description of ultrashort-pulse laser excitation of dielectric materials based on strong-field excitation in the Keldysh picture combined with a multiple-rate-equation model for the electronic excitation including collisional processes is presented. The model includes light attenuation in a self-consistent manner and changing optical properties described in a Drude picture. The model can be used to calculate the electronic excitation as a function of time and depth, and from these quantities the time-dependent optical parameters as well as the ablation depth can be derived. The simulations provide insight into the excitation and propagation dynamics of short-pulse excitation and show that at increasing fluence the excitation becomes localized near the material surface and gives rise to strong modifications of the optical properties of the material.

Wædegaard, K.; Sandkamm, D. B.; Haahr-Lillevang, L.; Bay, K. G.; Balling, Peter

2014-10-01

458

Three-Dimensional Roton Excitations and Supersolid Formation in Rydberg-Excited Bose-Einstein Condensates  

SciTech Connect

We study the behavior of a Bose-Einstein condensate in which atoms are weakly coupled to a highly excited Rydberg state. Since the latter have very strong van der Waals interactions, this coupling induces effective, nonlocal interactions between the dressed ground state atoms, which, opposed to dipolar interactions, are isotropically repulsive. Yet, one finds partial attraction in momentum space, giving rise to a roton-maxon excitation spectrum and a transition to a supersolid state in three-dimensional condensates. A detailed analysis of decoherence and loss mechanisms suggests that these phenomena are observable with current experimental capabilities.

Henkel, N.; Nath, R.; Pohl, T. [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany)

2010-05-14

459

Professionals and Emerging Scientists Sharing Science  

NASA Astrophysics Data System (ADS)

The Year of the Solar System (YSS) celebration begins in the fall of 2010. As YSS provides a means in which NASA can inspire members of the public about exciting missions to other worlds in our solar system, it is important to remember these missions are about the science being conducted and new discoveries being made. As part of the Year of the Solar System, Astromaterials Research and Exploration Science (ARES) Education, at the NASA Johnson Space Center, will infuse the great YSS celebration within the Expedition Earth and Beyond Program. Expedition Earth and Beyond (EEAB) is an authentic research program for students in grades 5-14 and is a component of ARES Education. Students involved in EEAB have the opportunity to conduct and share their research about Earth and/or planetary comparisons. ARES Education will help celebrate this exciting Year of the Solar System by inviting scientists to share their science. Throughout YSS, each month will highlight a topic related to exploring our solar system. Additionally, special mission events will be highlighted to increase awareness of the exciting missions and exploration milestones. To bring this excitement to classrooms across the nation, the Expedition Earth and Beyond Program and ARES Education will host classroom connection events in which scientists will have an opportunity to share discoveries being made through scientific research that relate to the YSS topic of the month. These interactive presentations will immerse students in some of the realities of exploration and potentially inspire them to conduct their own investigations. Additionally, scientists will share their own story of how they were inspired to pursue a STEM-related career that got them involved in exploration. These career highlights will allow students to understand and relate to the different avenues that scientists have taken to get where they are today. To bring the sharing of science full circle, student groups who conduct research by participating in Expedition Earth and Beyond, will also have the opportunity to virtually share their research. These virtual team presentations will allow these emerging scientists to celebrate their own exploration, and in doing so, contribute to the excitement of the Year of the Solar System. As the public joins NASA in the celebration of YSS, students across the nation will not only be excited by the science and discoveries being made, but will prime themselves with experience to perhaps someday become the new leaders in science, discovery, and NASA.

Graff, P. V.; Allen, J. S.; Tobola, K.

2010-12-01

460

K* couplings for the antidecuplet excitation  

SciTech Connect

We estimate the coupling of the K* vector meson to the N{yields}{theta}{sup +} transition employing unitary symmetry, vector-meson dominance, and results from the GRAAL Collaboration for {eta} photoproduction off the neutron. Our small numerical value for the coupling constant is consistent with the nonobservation of the {theta}{sup +} in recent CLAS searches for its photoproduction. We also estimate the K*-coupling for the N{yields}{sigma}* excitation, with {sigma}* being the {sigma}-like antidecuplet partner of the {theta}{sup +}-baryon.

Azimov, Ya. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation); Kuznetsov, V. [Kyungpook National University, Daegu, 702-701, Republic of Korea (Korea, Republic of); Institute for Nuclear Research, Moscow, 117312 (Russian Federation); Polyakov, M. V. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation); Institut fuer Theor. Physik -II, Ruhr-Universitaet, D-44780 Bochum (Germany); Strakovsky, I. [Center for Nuclear Studies, Physics Department, George Washington University, Washington, D.C. 20052 USA (United States)

2007-03-01

461

Magnetic excitations in nuclei with neutron excess  

E-print Network

The excitation of the $1^+$, $2^-$ and $3^+$ modes in $^{16}$O, $^{22}$O, $^{24}$O, $^{28}$O, $^{40}$Ca, $^{48}$Ca, $^{52}$Ca and $^{60}$Ca nuclei is studied with self-consistent random phase approximation calculations. Finite-range interactions of Gogny type, containing also tensor-isospin terms, are used. We analyze the evolution of the magnetic resonances with the increasing number of neutrons, the relevance of collective effects, the need of a correct treatment of the continuum and the role of the tensor force.

G. Co'; V. De Donno; M. Anguiano; A. M. Lallena

2012-03-13

462

Excitations of the Quark- Gluon Plasma  

E-print Network

We will discuss the spectrum of the eta mesons making use of the Nambu-Jona-Lasinio (NJL) model supplemented with a model of confinement. We will go on to discuss the properties of mesons at finite temperature and the phenomenon of deconfinement. We will then discuss some excited states of the quark-gluon plasma calculated in lattice QCD models.These resonances are thought to be created in heavy-ion collisions.We consider the role these states play in leading to a hydrodynamic description of the plasma at early stages of its formation.

C. M. Shakin; Huangsheng Wang; Qing Sun; Hu Li Xiangdong Li

2004-11-02

463

Observation of excited ?(b)(0) baryons.  

PubMed

Using pp collision data corresponding to 1.0 fb(-1) integrated luminosity collected by the LHCb detector, two narrow states are observed in the ?(b)(0)?(+)?(-) spectrum with masses 5911.97±0.12(stat)±0.02(syst)±0.66(?(b)(0) mass) MeV/c(2) and 5919.77±0.08(stat)±0.02(syst)±0.66(?(b)(0) mass) MeV/c(2). The significances of the observations are 5.2 and 10.2 standard deviations, respectively. These states are interpreted as the orbitally excited ?(b)(0) baryons, ?(b)(*0)(5912) and ?(b)(*0)(5920). PMID:23215180

Aaij, R; Abellan Beteta, C; Adametz, A; Adeva, B; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amhis, Y; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, C; Bauer, Th; Bay, A; Beddow, J; Bediaga, I; Belogurov, S; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bird, T; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Britsch, M; Britton, T; Brook, N H; Brown, H; Büchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Cauet, Ch; Charles, M; Charpentier, Ph; Chen, P; Chiapolini, N; Chrzaszcz, M; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Cogneras, E; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coombes, M; Corti, G; Couturier, B; Cowan, G A; Craik, D; Currie, R; D'Ambrosio, C; David, P; David, P N Y; De Bonis, I; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Del Buono, L; Deplano, C; Derkach, D; Deschamps, O; Dettori, F; Dickens, J; Dijkstra, H; Diniz Batista, P; Domingo Bonal, F; Donleavy, S; Dordei, F; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisele, F; Eisenhardt, S; Ekelhof, R; Eklund, L; El Rifai, I; Elsasser, Ch; Elsby, D; Esperante Pereira, D; Falabella, A; Färber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Fernandez Albor, V; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Francisco, O; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garra Tico, J; Garrido, L; Gascon, D; Gaspar, C; Gauld, R; Gauvin, N; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Greening, E; Gregson, S; Grünberg, O; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hampson, T; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; Harrison, P F; Hartmann, T; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hoballah, M; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Huston, R S; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kaballo, M; Kandybei, S; Karacson, M; Karbach, T M; Keaveney, J; Kenyon, I R; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Knecht, M; Kochebina, O; Komarov, I; Koopman, R F; Koppenburg, P; Korolev, M; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kruzelecki, K; Kucharczyk, M; Kudryavtsev, V; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Lesiak, T; Li, L; Li, Y; Li Gioi, L; Lieng, M; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; von Loeben, J; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Lu, H; Luisier, J; Mac Raighne, A; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Magnin, J; Malde, S; Mamunur, R M D; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Märki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martín Sánchez, A; Martinelli, M; Martinez Santos, D; Massafferri, A; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Maynard, B; Mazurov, A; McCarthy, J; McGregor, G; McNulty, R; Meissner, M; Merk, M; Merkel, J; Milanes, D A; Minard, M-N; Molina Rodriguez, J; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Müller, K; Muresan, R; Muryn, B; Muster, B; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nasteva, I; Needham, M; Neufeld, N; Nguyen, A D; Nguyen-Mau, C; Nicol, M; Niess, V; Nikitin, N; Nikodem, T; Nomerotski, A; Novoselov, A; Oblakowska-Mucha, A

2012-10-26

464

Single-neutron excitations near 132Sn  

NASA Astrophysics Data System (ADS)

Single-neutron excitations in neutron-rich tin isotopes have been studied with (d,p) reactions in inverse kinematics with accelerated beams of 124,126,128,130,132Sn. Reaction protons were measured with silicon strip detectors from ORRUBA. For the heavier isotopes, f and p single neutron configurations from across the N=82 gap dominate the spectra. Heavy-ion induced neutron transfer reactions have recently been measured with particle-gamma-ray coincidences. Measures of direct neutron capture can be obtained from the spectroscopic factors for p states. Plans to deduce the statistical component of neutron-capture cross sections are discussed.

Cizewski, Jolie A.; Jones, K. L.; Kozub, R. L.; Manning, B.; Nunes, F.; Pain, S. D.; Ribens Collaboration

2012-10-01

465

Photoinduced excitation energy transfer in hexapyropheophorbide a  

NASA Astrophysics Data System (ADS)

Comparative theoretical and experimental studies are reported on excitation energy transfer dynamics and linear absorption spectra of the supramolecular hexapyropheophorbide-a-complex in tetrahydrofuran solution. A mixed quantum-classical methodology was applied based on molecular dynamics simulation of the dissolved complex. The obtained nuclear trajectories together with precalculated potential energy surfaces and transition charges result in a time-dependent electronic Hamiltonian. The solutions of the related time-dependent Schrödinger equation together with an appropriate ensemble averaging allows to determine the linear absorption spectrum as well as the energy transfer. The strength of the method is demonstrated by good agreement between measured and computed data.

Megow, Jörg; Plehn, Thomas; Steffen, Ronald; Röder, Beate; May, Volkhard

2013-10-01

466

Directional excitation of graphene surface plasmons  

E-print Network

We propose a scheme to directionally couple light into graphene plasmons by placing a graphene sheet on a magneto-optical substrate. When a magnetic field is applied parallel to the surface, the graphene plasmon dispersion relation becomes asymmetric in the forward and backward directions. It is possible to achieve unidirectional excitation of graphene plasmons with normally incident illumination by applying a grating to the substrate. The directionality can be actively controlled by electrically gating the graphene, or by varying the magnetic bias. This scheme may have applications in graphene-based opto-electronics and sensing.

Liu, Fangli; Chong, Y D

2014-01-01

467

Excited triplet state spectroscopy in the infrared  

NASA Astrophysics Data System (ADS)

A new method for the investigation of the infrared spectra of metastable excitedelectronic states is presented. With a Fourier Transform infrared spectrometer as the probe and a CW Xe lamp source as the pump, the infrared spectrum of the lowest triplet state of triphenylene isolated in a N 2 matrix at 15K has been examined. CH out-of-plane wagging modes are prominent and shifted from their ground state frequencies. It is expected that when fully developed this method will provide important information on excited state force constants and potential energy surfaces.

Baiardo, Joseph; Mukherjee, Ranajit; Vala, Martin

1982-03-01

468

Collective plasmon excitations in graphene tubules  

NASA Astrophysics Data System (ADS)

Due to the inherent simplicity of the graphene tubule systems, it is expected that these systems will become model systems for the calculation of the mechanical and electronic properties of idealized carbon fibers. In this paper the collective electronic excitations on graphene tubules are discussed. The frequencies of the plasmons on graphene tubules are calculated using an empirical infinitely thin cylindrical-shell model within the framework of a two-fluid hydrodynamic description. There are two parameters involved in our calculation which are calibrated on graphite. The variations of plasmon frequencies and oscillator strength with the size of tube and longitudinal plasmon wavelength are discussed.

Jiang, Xudong

1996-11-01

469

Excited light isoscalar mesons from lattice QCD  

SciTech Connect

I report a recent lattice QCD calculation of an excited spectrum of light isoscalar mesons, something that has up to now proved challenging for lattice QCD. With novel techniques we extract an extensive spectrum with high statistical precision, including spin-four states and, for the first time, light isoscalars with exotic quantum numbers. In addition, the hidden flavour content of these mesons is determined, providing a window on annihilation dynamics in QCD. I comment on future prospects including applications to the study of resonances.

Christopher Thomas

2011-07-01

470

Spiral Wave Generation in Heterogeneous Excitable Media  

NASA Astrophysics Data System (ADS)

As the coupling in a heterogeneous excitable medium is reduced, three different types of behavior are encountered: plane waves propagate without breaking up, plane waves break up into spiral waves, and plane waves block. We illustrate these phenomena in monolayers of chick embryonic heart cells using calcium sensitive fluorescent dyes. Following the addition of heptanol, an agent that reduces the electrical coupling between cells, we observe breakup of spiral waves. These results are modeled in a heterogeneous cellular automaton model in which the neighborhood of interaction is modified.

Bub, Gil; Shrier, Alvin; Glass, Leon

2002-02-01

471

Electron-impact vibrational excitation of furan  

SciTech Connect

We report measurements of differential cross sections for the vibrational excitation of furan (C{sub 4}H{sub 4}O), obtaining results for nine features spanning the electron energy loss range from 0 to 0.8 eV, at electron-impact energies of 5, 6, 7.5, 10, and 15 eV and for scattering angles ranging from 10{sup o} to 130{sup o}. The normalization of the differential cross sections was done using elastic differential cross sections for furan determined earlier by our group [Khakoo et al., Phys. Rev A 81, 062716 (2010)].

Hargreaves, L. R.; Albaridy, R.; Serna, G.; Khakoo, M. A. [Department of Physics, California State University, Fullerton, California 92834 (United States); Lopes, M. C. A. [Departamento de Fisica, ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG, CEP 36036-330 (Brazil)

2011-12-15

472

Electron-impact vibrational excitation of furan  

NASA Astrophysics Data System (ADS)

We report measurements of differential cross sections for the vibrational excitation of furan (C4H4O), obtaining results for nine features spanning the electron energy loss range from 0 to 0.8 eV, at electron-impact energies of 5, 6, 7.5, 10, and 15 eV and for scattering angles ranging from 10o to 130o. The normalization of the differential cross sections was done using elastic differential cross sections for furan determined earlier by our group [Khakoo , Phys. Rev APLRAAN1050-294710.1103/PhysRevA.81.062716 81, 062716 (2010)].

Hargreaves, L. R.; Albaridy, R.; Serna, G.; Lopes, M. C. A.; Khakoo, M. A.

2011-12-01

473

Parity doubling of highly excited mesons  

E-print Network

Glozman has proposed that highly excited mesons and baryons fall into parity doublets, and that the f4(2050) on the leading Regge trajectory should have a nearly degenerate J^{PC} = 4^{-+} partner. A re-analysis of Crystal Barrel data does not support this idea. A likely explanation is that centrifugal barriers on the leading trajectory allow formation of the L=J-1 states, but are too strong to allow L=J states. Two new polarisation experiments have the potential for major progress in meson spectroscopy.

D. V. Bugg

2009-08-10

474

Electron-impact excitation of atmospheric gases  

NASA Astrophysics Data System (ADS)

Electron energy-loss and impact-induced emission techniques were used to investigate excitation of key features in molecular nitrogen and rare gases. Specifically, line and band emission intensities were investigated as a function of wavelength (at high resolution) and incident electron energy using various monochromator-detector combinations. In addition, electron energy-loss spectroscopy was utilized such that differential cross sections (DCSs) and integral cross sections (ICSs) were obtained. The emission cross sections, DCSs, and ICSs for these atmospheric species will be presented.

Malone, Charles P.; Young, Jason A.; Johnson, Paul V.; Liu, Xianming; Kanik, Isik; Ajdari, Bahar; Khakoo, Murtadha A.

2010-03-01

475

Rabi resonances in the {lambda} excitation scheme  

SciTech Connect

We consider the interaction of a three-level system with phase-modulated resonant fields in the {lambda} excitation scheme. We treat theoretically the case of a sinusoidal phase modulation, a phase step perturbation, and a stochastic phase modulation. The appearance of a Rabi resonance both in the spectrum of the optical transmitted signal (electromagnetically induced transparency) and in the spectrum of the microwave emission (coherent population trapping maser) is considered in detail. All the theoretical results are compared with the analogous ones reported for the two-level system and with our experimental observations obtained for the case of rubidium in a buffer gas.

Godone, Aldo; Micalizio, Salvatore; Levi, Filippo [Istituto Elettrotecnico Nazionale 'Galileo Ferraris', Strada delle Cacce 91, 10135 Torino (Italy)